Marine Vertebrates Flashcards

Question

Sensory adaptations of Pinnipeds

Answer 1

Pinnipeds - Muscles and a cartilage valve along the external ear canal function to close the ear canal to water But inner ear similar to humans and land mammals…. Outer ear collects and directs sound > Middle ear filter and amplifies > Inner ear acoustic sound > electric nerve > brain

Answer 2

Mammals make noise with their larynx Pinnipeds, baleen whales have larynx that makes noise. Mysticetes only use larynx – it has a U-shaped fold (similar to vocal chords Odontocete use larynx but with specialized air sacs (by blow hole) = whistles, clicks etc. Channeled through melon Baleen whales contract muscles in the throat and chest, causing air to flow between the lungs and the laryngeal sac. Alternating expansion and contraction of the lungs and sac drives air across the u-fold, causing it to vibrate and produce sound. Vibrations from the laryngeal sac may propagate through the ventral throat pleats into the surrounding water as sound waves. Changes in the laryngeal sac shape may alter the frequency and/ or amplitude of sounds produced

Answer 3

Cranium telescoping: results in multi-layered skull influencing the pathway of sound into the head Attachment of auditory apparatus: not attached to skull but floats in an insulated environment important for echo-location No air-filled outer canals: have specialised fatty tissue connection The variable thickness of the basilar membrane influences the thickness of the cochlea spire which regulates what frequency of sound that can be detected

Answer 4

Match receptor pigment sensitivity - to match light environment e.g. open ocean cetaceans maximum sensitivity at the blue end of the spectrum Increase density of photoreceptors Enhance photon capture - by modification & thickening of the tapetum (reflective layer)

Answer 5

Visual acuity (ability to resolve fine details) 1. Focusing ability of the optic in the eye 2. Density of receptors in the retina 3. The connection between receptors 4. Processing of the signal in the CNS The strength of the eye lens depends on: 1. Refractive index 2. The extent of lens curvature

Answer 6

Chemoreception Inverse relationship between adaptations to a marine existence and development of olfactory senses Absent or poor in cetaceans; rudimentary in sirenians; aspect of behavioural ecology of pinnipeds e.g. mating and pup ID

Answer 7

Cetacean are tactile, mostly so around blow-hole = air / water interface Major tactile mechanism = vibrissae e.g. rostrum of cetaceans, “whiskers” of pinnipeds & sea otters

Answer 8

Only really investigated in cetaceans due to large migrations in great whales - probably utilise earth’s magnetic field - Underlying mechanism not clearly understood but magnetite has been identified in the brains of several cetacean species

Answer 9

Brain Morphology Communication -Language and Thought -Syntax and Reference Emotional intelligence -Self-awareness, empathy and altruism Imitation and Social Learning Behavioural responses

Answer 10

Brain Morphology Communication -Language and Thought -Syntax and Reference Emotional intelligence -Self-awareness, empathy and altruism Imitation and Social Learning Behavioural responses

Answer 11

Brain morphology suggests high intelligence Observational science suggests relatively high intelligence Mostly supported by tests but tests are sometimes bias or in appropriate Intelligence appears to be directly associated to the need to form strong social bonds and networks to remain fit

Answer 12

Dolphins seem to adjust their heart rates as they dive to avoid decompression sickness, also known as the bends, which is caused by sudden changes in pressure. Human divers must avoid surfacing too quickly as the drop in pressure can force nitrogen bubbles into their airways and cause joint pain or even paralysis.

Answer 13

Production and storage of sperm The ratio of testes to body size does vary inter-specifically Size of testis related to sexual behaviour – males competing for females with high copulatory rates - bigger testes Odontocete have very high i.e. testes : body mass – 7-25 x higher than predicted for terrestrial mammals; seasonality in development Dusky dolphins have the record = 8 % (of bd. Wt. = testes) Humans invest about 0.08 % Similarly in Mysticete – biggest Right whales > 900 kg testes Penis – can retract into the body Actual structure similar to terrestrial mammals

Answer 14

Estrous cycle has two phases (similar to terrestrial) : Follicular phase : estradiol → GnRH → FSH – follicle formation Luteal phase: progesterone – inhibits ovulation, reduced contraction and enables pregnancy Phases vary in length between species

Answer 15

As long-lived : -rates of reproduction are low -low regeneration potential if populations are impacted -have low resilience to environmental perturbations One of the universal features of reproduction in marine Carnivora is delayed implantation The timing of the delayed implantations is the key in the event of the reproductive cycle which is controlled by photoperiod and nutrition The time of implantations represents reactivation of the reproductive system after a period of quiescence – is species specific

Answer 16

Distinctive features of pinniped reproduction include: -Delayed implementation -Highly seasonal and synchronised reproductive cycles -The production of a single pup Male Pinnipeds –annual cycle of testicular regression and growth Mean annual pregnancy rates between 0.5 and 0.9 appear to be normal There can be annual variations which results from changes in population density and resource availability Mating and breeding seasons are combined

Answer 17

Do not return to land / ice for birth and reproduction is a-seasonal Male otters do not appear to have any seasonal cycles Sea Otters do have a period of delayed implantation but is highly variable. Gestation is about 6-8 months. But the period of active foetal growth is more likely to be between 4.5 – 5.5 months Time between reproduction cycles > 1y because the pups tend to be nursed for 4 – 8 months Annual birth rates - 0.5 – 0.9, but generally sea otter reproduction biology is not well known

Answer 18

Reproduction cycles are dominated by the annual cycles of sea ice. The breeding season occurs between March and May Delayed Implantation occurs for about 4 – 5 months ending when females reach their wintering dens during late September Gestation is only 3 – 4 months and consequently the new offspring are fairly poorly developed at birth: Mean litter sizes of 1.9 The annual mean pregnancy = % of females in a population that are pregnant or lactating / gestation period in years 0.3 – 0.6 Interval between birth generally about 3.1 – 3.6 years (high infant dependency)

Answer 19

Pollution 1. Marine debris - ingestion and drowning 2. Toxic compounds (e.g. PCB’s and oil) 3. Sewage - introduction of pathogens 4. Radiation - cancers 5. Noise pollution - exclusion from preferred habitats

Answer 20

Culling deemed unreasonable because of:- 1. Economics - culling usually heavily subsidised and no evidence to suggest less seals = more fish 2. Socially - no social or cultural reasons for culling (exception - some traditional hunters) 3. Scientifically - cannot predict cascade effects – fisheries must prove there is a benefit of culls not other way around 4. Humane - clean kills rare - pointless suffering

Answer 21

1. Fisheries related: by-catch and prey depletion 2. Noise pollution : e.g. exploration for gas etc 3. Chemical pollution: - a. Heavy metals b. Organochlorines c. PCB’s 4. Physical habitat destruction:- a. Deforestation b. River diversion and habitat manipulation c. Coastal development d. Energy production e.g. barrages e. Land reclamation e.g. for mariculture 5. Global environmental change: ozone depletion and global warming

Answer 22

All sirenians listed as endangered or vulnerable by the IUCN Exasperated by :- 1. Slow reproductive rate 2. Long gestation period 3. Slow growth rate Several threats:- 1. Habitat destruction: often through development and land reclamation. 2. Hunting for :- a. Meat e.g. Moslems pork substitute b. Religious festivals e.g. Sri Lanka c. Soles of sandals e.g. Red Sea d. Oil - traditionally thought to be medicinal e. Powered bone - medicinal f. Dugong ivory - jewellery g. Dugong tears – aphrodisiac 3. Power boat collisions - esp. Florida (200 per y-1). 4. Toxic algal blooms -respiratory problems.

Answer 23

Any of numerous cold-blooded (poikilothermic/ectothermic) aquatic vertebrates of the class Osteichthyes (bony skeleton) or Chondrichthyes (cartilaginous skeleton), characteristically having fins, gills and a streamlined body. THERMAL STRATEGIES  Based on stability of body temperature o Poikilotherm – variable body temperature o Homeotherm – stable body temperature  Based on the sources of thermal energy o Ectotherm – environment source of heat form environment o Endotherm – animal generates internal heat to maintain body temperature Heterothermy occurs in animals which are able to switch from endothermy to ectothermy

Answer 24

The relationships between fish morphology, environment and lifestyle An otolith, (oto-, ear + lithos, a stone) or otoconium is a structure in the saccule or utricle of the inner ear. It is comprised of a combination of a gelatinous matrix and calcium carbonate crystals. Otolith crystals are relatively dense and heavy - they are connected to the rest of the body by the sensory processes of the macular cells. In fish, otoliths can be used for age determination, showing rings of different growth summer/winter, like tree rings. Fins supported by more complex skeletal and muscle arrangments – more control over swimming motion – can move backwards, hover mid watewr etc.. Swim bladder – secretory, reabsorption and storage – gas gland accumulates oxygen and nitrogen against a pressure gradient Mackeral and tuna – no swim bladder ineffciency of swim bladder to adjust quickly to change sin pressure

Answer 25

Gelatin-filled tunnel containing clusters of nerve cells for detecting vibrations -runs beneath skin along each side from tail to head -detects reflections of bow waves off nearby objects, incl. other fish Allows rapid movement near solid surfaces and tight schooling

Answer 26

Fusiform – many pelagic species, streamlined, e.g. tuna, herring. Attenuate (sometimes ‘anguilliform’) – elongated, e.g. needlefish, eels. Filiform - threadlike, e.g. pipefish, snipe eel Globiform – spherical, e.g. puffer, lumpfish Compressed dorso-laterally – flattened side-to-side, e.g. flounder, sole, plaice, butterfly fish. Compressed dorso-ventrally (or ‘depressiform’) – flattened top to bottom), e.g. Sea moth, rays. Early life stages (e.g. larvae, fry) of many fish are fusiform when pelagic - change shape as they mature. Body form reflects habitat and lifestyle

Answer 27

Fish swimming gaits can be divided into two functional groups: (1) body-caudal fin gaits vs. (2) median-paired fin gaits 1. involve undulation of the body and caudal fin to create thrust 2. powered by one or more medianor paired fins, while the body is held rigid

Answer 28

Anguilliform – the full body wave creates a backward-facing “wall” that pushes against the water Thunniform – all about thrust from the lunate tail. Has reduced drag compared to full body wave swimming. Ostraciiform - Caudal fin oscillates - useful for odd-shaped fishes, e.g. boxfish and puffer fish

Answer 29

Labriform [wrasse-like] - pectoral fins beat – like rowing. Useful for fine maneuvering, e.g. wrasse and parrotfish Balistiform – dorsal and anal fins undulate allowing the fish to move by sculling, e.g. trigger fish. Amiiform – dorsal fin undulates. Good for stalking or moving without disrupting body musculature, e.g. oarfish, seahorse Gymnotiform – anal fin undulates – e.g. knife fish that produce and sense electrical impulses from their body

Answer 30

Semelparity – single event then die (e.g. Pacific Salmon are a semelparous species) a life history adaptation in which all of an organism's reproductive resources are focused on a single, large reproductive event, then it dies Iteroparity - more common: repeated reproduction (e.g. Cod are an iteroparous species) a life history adaptation in which an organism produces offspring several times over many seasons Parental investment? Life history patterns determine how an animal’s energy intake is allocated - evolved to optimize tradeoffs between growth, survival & reproduction. Classic tradeoff = larger eggs, fewer of them.

Answer 31

Non-guarders - open substrate spawners – scatter eggs, spawn in large groups a. Pelagic spawners – schooling fish such as Tuna (Scombridae) and sardines (Clupeidae). b. Benthic – eggs adhesive – stick to substrate or in long strings to attach to surface of substrate, sturgeons, carp, pike c. Brood hiders -bury eggs, for example Salmon (build redds, bury eggs)

Answer 32

88% of teleosts = gonochorists or dioecious = either male or female at any one time. Sex – determined genetically (Genetic Sex Determination - GSD) or by environmental conditions in early stage of development (Environmental Sex Determination - ESD). Sex in some teleosts determined by interaction of genes and environment [GxE]. Functional hermaphroditism – rare in other vert groups but about 2% teleosts (= 30 families) In some gonochoristic species, the gonad initially develops as an ovary even in individuals that eventually become male [sequential hermaphroditism]

Answer 33

In bony fish, most Teleosts are dioecious, but many families in tropical regions have hermaphroditic species. Hermaphrodites can be: 1. Synchronous – individuals possess active ovarian and testicular tissue. Relatively atypical, a few Serranids, sea basses, e.g. Serranus sp.). When would this strategy be an advantage? 2. Sequential – can change sex - both male & female organs may be present but only 1 active at given time. 2a. Protogynous - most common. Female  male (e.g. Parrotfishes, Wrasses, Groupers). Dominant male removed – largest female becomes male (large male can monopolise breeding). 2b. Protandrous Male  female (NEMO!)

Answer 34

Hard to define! Migrations typically feature at least one of the following concepts: Directed movement. Extended duration & distance. Seasonal to-and-fro. Population redistribution.

Answer 35

Diel – daily (e.g. juvenile fishes to/from mangroves, small fish and zooplankton to/from surface waters) Ontogenetic – across life stages (e.g. juvenile inland nursery grounds -> offshore adult feeding grounds) This is done so adult fish do not accidently eat their young because they cannot identify their young. Seasonal – annual seasonal movements between feeding and spawning grounds (e.g. sharks, whales, capelin, plaice… lots) Diadromous – between freshwater and sea (e.g. salmon = anadromous = spawn in FW; eels = catadromous = spawn in sea) Amphidromous - born in FW/estuaries, drift to sea as larvae before migrating back to FW to grow into adults and spawn. Potamodromous – migrate only within freshwater (e.g. lake sturgeon) Oceanodromous – migrate only in sea (e.g bluefin tuna) Note: a single fish species may perform multiple types of migration across their lifetime!

Answer 36

Tracking conditions that increase fitness - e.g. tracking resources such as plankton blooms, tracking warmer temperature for growth/egg development, incoming tides that open up foraging areas. Avoiding conditions that reducing fitness Reducing predation and providing optimum environment / refuge for offspring - e.g. nearshore/estuarine nursery grounds; diel migration of prey fish to and from mangroves (Laegdsgaard and Johnson, 2001). Reducing inter and intraspecific competition, and cannibalism – ontogenetic niche shifts (migrations of adults from nursery areas reduces the potential for cannibalism - eating your own offspring is a quick way to reduce your fitness!)

Answer 37

Yellow fin tuna are heterothermic and can control their body temperature when they need to dive deeper to hunt for food

Answer 38

We can use satellite tags. However, we can only use them on larger fish due to the tags being heavy. You can also study their ear-bones to see how old the fish is. Finally you can use the fish's eyes and peel back layer after layer, revealing what the fish has eaten during its lifetime using the concentration of isotopes

Answer 39

-Climate change (warming/extreme weather) -hypoxia (dead zones) -pollution/plastics -fishing and aquaculture -ocean acidification -habitat loss/ fragmentation Temperature and metabolism intrisically linked Increased metabolism = increased demands on energy = More food needed to survive Impacts disproportionately on recruitment = smaller fish have less reserves built up to rely upon Larval fish close to energetic limits – growth trajectories Energetic cost of forming bone increases as minerals remain dissolved more readily Maintaining internal pH comes with greater costs Increased demands on energy = More food needed to survive Impacts disproportionately on recruitment Larval fish close to energetic limits – growth trajectories PLASTICS: Impaction of stomach – leading to starvation and death Even if passed through energetic cost is still present of digestion and capture MINUS any of the energetic pay off of food Impacts disproportionately on recruitment = smaller fish = smaller guts = greater risk Behavioural response – shifting distributions towards poles.

Answer 40

Tropical and Temperate species Globally distributed. Mostly marine but about 5% of elasmobranch species are obligate freshwater species (only stingrays) or euryhaline (multiple families). Often long-lived – Greenland shark is an extreme (one was estimated as between 272 and 512 years old!) Often exhibit counter shading (dark on top, pale underneath for camouflage).

Answer 41

The primary aspect that gives sharks and rays buoyancy is a large liver filled with low-density oil. Cartilaginous skeleton may also serve to aid buoyancy; cartilage is about half the density of bone and a frame composed of cartilage would be considerably lighter than the same one composed of bone. Also body shape/profile (flattened snouts and belly). Finally, some sharks employ air gulping as a way of controlling their buoyancy. There are several species in which air gulping is well known; most are the aptly-named swellsharks (members of the catshark family). In most instances, they use this method to wedge themselves in rock crevices so that predators cannot dig them out. One shark that uses air gulping to an entirely different end is the sandtiger shark – which gulp air at the surface, holding it in their stomachs and “farting” it out gradually until the desired depth is achieved. This retention of air allows the shark to hover almost motionless at a depth of its choosing. The lateral line is a system of sensory organs found in aquatic jawed vertebrates, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial cells, known as hair cells, which respond to displacement caused by motion and transduce these signals into electrical impulses via excitatory synapses. Lateral lines serve an important role in schooling behavior, predation, and orientation. IN ELASMOBRANCHS they have evolved additional electroreceptors to sense smell and electric fields – e.g. Ampullae of Lorenzini OSMOREGULATION How do sharks cope with freshwater? Elasmobranchs keep their internal environment close to equilibrium with sea water by having a high concentration of urea in their blood and excreting salts through a specialised organ, the rectal gland. When entering freshwater, euryhaline elasmobranchs are able to excrete urea and take salt from the environment through their gills. freshwater fishes. Because the salt concentration inside their body is higher as in the surrounding water, water enters the body due to osmosis. To compensate, the kidney produces a large amount of urine, which at the same time means loss of salts. To maintain a sufficient salt level, special cells in the gills (chloride cells) take up ions from the water, which are then directly transported into the blood. In contrast, marine fishes face the opposite challenge – since the salt content in their blood is much lower than that of seawater, they constantly tend to lose water and build up salt. To replace the water loss, they continually drink seawater. Since their small kidney can only excrete relatively small amount of urine, the excretion of salt additionally takes place in the gills where chloride cells work in reverse as in freshwater fishes Paired fins No swimbladder: All sharks are slightly negatively buoyant, which means they sink. Unlike many bony fishes, sharks do not have a swim bladder to provide buoyancy. To help compensate for their tendency to sink, their livers contain large amounts of oil that is less dense than seawater. Paired gill slits Cartilaginous skeleton Clasping fins for reproduction Placoid scales Sensory system? Visual (eyes) Olfactory (nostrils) Hearing (inner ear, but no swim bladder) Touch/pressure (lateral line) Electroreception (Ampullae of Lorenzini)

Answer 42

Placoid scales are found in sharks and rays, and can vary greatly in external appearance. Unlike the scales of bony fishes, placoid scales do not increase in size as the fish grows, instead new scales are added between older scales. Placoid scales are often referred to as denticles. Placoid (pointed, tooth-shaped) scales are found in the cartilaginous fishes: sharks, rays. They are also called dermal denticles. Placoid scales are structurally homologous with vertebrate teeth ("denticle" translates to "small tooth"), having a central pulp cavity supplied with blood vessels, surrounded by a conical layer of dentine, all of which sits on top of a rectangular basal plate that rests on the dermis. The outermost layer is composed of vitrodentine, a largely inorganic enamel-like substance. Placoid scales cannot grow in size, but rather more scales are added as the fish increases in size. FUNCTIONS???? Protection (placoid scales can be very sharp), camouflage (often silvery), reduce energy cost (drag)

Answer 43

Electroreceptors mostly found in cartilaginous fish. Described by Stefano Lorenzini in 1678. Sensitive to electric fields and changes in temperature, mechanical pressure & salinity. Rather than an adaptation specific to elasmobranchs, seems to be something that was lost from other groups (e.g. terrestrial spp and teleosts) The ampullae of Lorenzini are small vesicles and pores that form part of an extensive subcutaneous sensory network system. These vesicles and pores are found around the head of the shark and are visible to the naked eye. They appear as dark spots in the photo of a porbeagle shark head below. The ampullae detect weak magnetic fields produced by other fishes, at least over short ranges. This enables the shark to locate prey that are buried in the sand, or orient to nearby movement. Recent research suggests that the ampullae may also allow the shark to detect changes in water temperature. Each ampulla is a bundle of sensory cells that are enervated by several nerve fibers. These fibers are enclosed in a gel-filled tubule which has a direct opening to the surface through a pore. The gel (a glyco-protein based substance) has electrical properties similar to a semiconductor, allowing temperature changes to be translated into electrical information that the shark can use to help detect temperature gradients. Rays use Ampullae of Lorenzini – Electroreception to find prey in substratum – e.g. experimental design in paper below.

Answer 44

“Electric” rays – Torpediniformes (can produce electrical dischange > 200 V!) e.g. Common Torpedo (Torpedo torpedo) Skates – Rajiformes e.g. Thornback ray (Raja clavata) and the critically endangered “Common” skate (Dipturus batis). In both cases, the name is misleading! Rays – Myliobatiformes e.g. The eagle rays (Myliobatis spp) and the Manta rays (Mobula spp). Guitarfishes, Banjo rays, Wedgefishes, sawfishes - Rhinopristiformes

Answer 45

Dorsoventrally flattened [‘depressiform’] Largely inhabit benthic habitats Eyes on top, mouth and gills underside Ventilation through spiracles (Mostly) Feed on invertebrates and fish hidden in benthos (Mostly) heavy round crushing teeth converse to sharp pointed teeth Sensory adaptations to detect electrical fields of prey Defence = venomous barb; electric shocks; camouflage by burying in sand/mud.

Answer 46

1) High-speed cruisers e.g. Great white shark (Carcharodon carcharias) 2) Generalized, continental swimmers, e.g. Thresher sharks (Alopias spp) 3) Slow swimming epibenthic, benthic, and demersal sharks e.g. catsharks (Scyliorhinus spp). 4) The leftovers! Variety of body shapes. Lack an anal fin and are often deep-sea, e.g. spiny dogfish (Squalus spp)

Answer 47

Like teleosts, elasmobranchs acquire O2 through gills using “countercurrent oxygen exchange” (blood flows through gills in the opposite direction to the water flowing over the gills). Though both sharks and rays use gill slits to breath underwater, they tend to breath differently. First of all rays have gill slits on the underneath side of their bodies, while sharks tend to have gill slits on the sides of their heads. Rays breathe by sucking in water through their spiracles and exhale it over their gills. Sharks on the other hand breath in two ways depending on the species. They either ram breath which means they swim through the water passing it over their gills or they pull in water through their mouths and over their gills. So sharks tend to be more active swimmers in order to breath, while rays can sit still for long periods. BUCCAL PUMPING. Most fish (teleosts, skates, rays, some sharks, e.g. nurse sharks) use ‘buccal pumping’ (opening/closing mouth to pump water through mouth and over gills). VIA SPIRACLES. Benthic batoids and sharks can also sometimes draw water in through spiracles (openings behind eyes) to avoid sand contamination RAM VENTILATION. Large, pelagic sharks (e.g. great white, mako, whale shark, blue shark) and some teleosts (tunas and billfishes) are ram ventilators - forcing water through mouth by swimming forward (Note: obligate ram ventilators = only ~25 of the ~470 total shark species).

Answer 48

Mating: sharks ‘advanced’ reproductive features: - internal fertilisation Sexually dimorphic. Males have pelvic claspers [modified pelvic fins for sperm delivery]. NOTE: Males also have a cloaca (Latin: “sewer”!) = common chamber into which the intestinal, urinary, and genital tracts open (common to amphibians, reptiles, birds, elasmobranch fishes - NOT present in most mammals or teleosts). Also skin thickness! The skin on a female blue shark is nearly twice as thick as that of males, probably to avoid injuries from mating. Males will often bite females during face to face copulation. Multiple paternity is thought to be more common in shark species whose females can store sperm after mating for later use and in species that gather together at breeding time, which increases the number of available mates. It may have advantages for both sexes, increasing genetic diversity within a litter, countering the risks of inbreeding if the population is small and isolated, and increasing mating opportunities for males.

Answer 49

oviparous: lay fertilized eggs in water [all skates] viviparous: Give birth to live young. Internal gestation, nourished by parent ovoviviparous: Form of viviparity. Give birth to live young. Internal gestation, nourished by egg. [most sharks and rays]

Answer 50

43% of all Chondrichthyes, including many sharks and ALL skates (Rajidae) eggs in leathery cases varying forms up to 15 months to hatch Young are born as miniature adults Eggs laid low compared to bony fish 10s -100s rather than 1000s – 100000s

Answer 51

57% of elasmobranchs (in all its various forms, i.e. including ovoviviparity) Yolk sac becomes attached to maternal uterine wall to form yolk sac placenta. Foetus is nourished via this placenta (i.e. convergent evolution). Watch a lemon shark give birth: https://www.youtube.com/watch?v=LfQgRCg1bNA Gestational period varies greatly, but most sharks carry their pups from 7 months to three years. Viviparous rays Myliobatiformes – stingrays and eagle rays Uterine viviparity: No placenta, but nourish embryos after yolk sac is depleted by secreting ‘uterine milk’.

Answer 52

“Aplacental viviparity” = THE MOST COMMON FORM OF REPRODUCTION FOR SHARKS & RAYS [but not skates!!] Yolk sac ovoviviparity - thinner shelled eggs retained inside the female. Young hatch inside female once yolk food supply is exhausted and are born. Retained ovoviviparity – eggs laid when nearly ready to hatch, kept inside female until then. e.g. some Catsharks, Scyliorhinidae). The major difference between rays and skates is in their reproductive strategies. Rays are live bearing (viviparous) while skates are egg laying (oviparous), releasing their eggs in hard rectangular cases sometimes called “mermaid’s purses”. Also, skates typically have a prominent dorsal fin while the dorsal fin is absent or greatly reduced in rays.

Answer 53

Cannibal viviparity 1) embryonic cannibalismSand Tiger shark (Carcharias taurus) exhibits uterine cannibalism feeding on the other embryos (embryophagy). First foetus to develop consumes other foetuses coming down oviduct, then reverts to unfertilised eggs. Has developed primitive teeth for this. Oophagy Lamniform sharks (Thresher sharks Alopias spp) feed on bundles of unfertilised eggs in female reproductive system leaving only 1 offspring per uterus (i.e. 2 total).

Answer 54

Still little known about shark migration. Difficult to study: numbers are few, not easy to catch or tag. No otoliths. Usual cycle = feeding area(s) -> spawning area / nursery. They often return to the same spawning grounds

Answer 55

They have a long gestation period and take a long time to mature. meaning they will be driven to extinction very easily from overfishing. It is also cruel since they are mainly fished for shark-fin soup which is very niche.

Answer 56

1. Ampullae of Lorenzini 2. Oviparous – Egg laying 3. Thunniform – I might allow carangiform 4. Altered behaviour, food quality and health, etc 5. Mating with multiple males 6. Oil content in Liver 7. Demography – sex ratios, juveniles vs adults, size/age structure, distribution, survivorship, etc

Answer 57

Acoustic communication large whales produce low frequency sound - well below our detection limits Dolphins can hear sounds > 5x our upper hearing limit Large variations Humans speak by passing air through the larynx or the voice box. Cetacean sound production is very different. The precise mechanism differs in the two major suborders of cetaceans: 1) Odontoceti (toothed whales—including dolphins, pilot whales, beaked whales, killer whales, sperm whales, narwhals, and beluga whales) use phonic lips or monkey lips that evolved from what was the nose, 2) Baleen whales do not have phonic lip structure. Instead, they use a larynx, but unlike ours it lacks vocal cords and whales do not have to exhale in order to produce sound, but likely recycle air around the body for this purpose. Humans with normal hearing can hear sounds between 20 Hz and 20,000 Hz (often only really 20-5000 Hz or 0.02-5kHz)

Answer 58

Humans pollute in many ways! Main causes of noise pollution: 1. Shipping 2. Seismic airguns - Seismic exploration surveys generate the loudest human sounds in the ocean, short of those made by explosives. The blasts — which can reach more than 250 decibels and be heard for miles — can cause hearing loss in marine mammals, disturb essential behaviors such as feeding and breeding, mask communications. Seismic testing involves producing blasts of air (a kind of powerful horn) repeatedly then measuring the echoes to map offshore oil and gas reserves. 3. Sonar- The depth of the ocean can be measured using a device called SONAR (Sound Navigation And Ranging). Sonar works by sending out sound waves and measuring how long it takes for the echo to return. If the water is shallow, sound waves that reflect off the bottom of the ocean will return faster than in deep sea.

Answer 59

High frequency clicks and buzzes to detect the echoes of these clicks as they bounce off distant objects Odontoceti are the only group of mammals which have this ability. A dolphin can detect a squash ball a football pitch away. Shapes and composition can be determined Odontocetes produce rapid bursts of high-frequency clicks and buzzes thought to be primarily for echolocation – “biosonar” - using specialized organs (phonic lips evolved from what was dolphin nose). Echoes from clicks convey distance to target, size, shape, speed, and vector of its movement. And differences in density or material composition. Also produce whistles for communication among conspecifics ("signature whistles" are distinctive to the individual and may serve as a form of ID). Frankel quotes one researcher who says listening to a school of odontocetes is like listening to a group of children at a school playground. Bulla (inner ear) – receives incoming echoes via tymanic plates and middle/inner ear The precise mechanism for how the sonic image is then ‘read’ by the cochleae is still unknown. Working hypothesis = wave propagates along basilar and tectoral membrane situated in the heart of each cochlea. Microscopic cilia connect with the tectorial membrane and ‘read’ the shape of the imprint, creating a composite electrical signal representing the object’s shape. This electrical signal travels to the brain via the cochlea nerve and is interpreted as an image.

Answer 60

“Increases in ship noise, both within and below the dolphins' call bandwidth, resulted in higher dolphin whistle frequencies and a reduction in whistle contour complexity, an acoustic feature associated with individual identification. Consequently, the noise-induced simplification of dolphin whistles may reduce the information content in these acoustic signals and decrease effective communication, parent–offspring proximity or group cohesion.” It may also cause "The bends"

Answer 61

Emit low frequency sound between 10 - 30 Hz - as loud as a medium sized ship. The higher the frequency the more energy is lost from the sound signal via heat production Greatest sound level concentrated at the SOFAR (Sound Fixing And Ranging) channel - the speed of sound is at its minimum and becomes concentrated Imagine water absorbing into a tissue. Molecules are getting caught within the medium Acoustic energy > heat e.g. by causing them to vibrate. SOFAR (Sound Fixing And Ranging channel)= water layer where the speed of sound is at its minimum. The up-and-down bending of low-frequency soundwaves allows soundwaves to travel great distances without the signal losing significant energy. Think of the ocean as consisting of various zones, or layers — sort of like oil and vinegar salad dressing before it’s shaken up — except that ocean layers occur due to differences in salinity (salt content) and temperature variations. Saltier and colder water lie beneath less salty, warmer water. SOFAR - Sound Fixing And Ranging channel - zone in the oceanic water column at a depth of about 1500 m, where the velocity of sound is at a minimum value. Sound passing through the zone is refracted upwards or downwards back into the zone, with little loss of energy, causing sound energy to be trapped in a zone of well-defined depth. Sound waves also converge at the surface approx. every 50 km - increase sound levels x10 – may be utilised by communicating cetaceans

Answer 62

Possibly male - male interactions Evidence:- 1. Songs do maintain distance between males 2. Females do not respond to playback songs 3. Singing males show increased aggression towards each other Females also probably used it as male selection criteria By utilising the convergence zones (SOFAR channel to deep) females could listen in to many males singing over large areas Other cetacean songs tend to be much simpler Generally used as a reproductive advertisement display Pinnipeds can produce airborn and underwater vocalizations such as barks, grunts, rasps, rattles, growls, creaks, warbles, trills, chirps, chugs, clicks and whistles.

Answer 63

Have well-defined social structure and exist in pods that do not change Line ritual (greeting ceremony) - tactile communication Each pod has a unique song repertoire and may adapt vocalizations according to their feeding preferences (see Deeke et al. 2005) Communicative generally during feeding and travelling and serves to:- a. Indicate pod affiliation b. Maintain pod cohesion c. To co-ordinate activities of pod members Females also may use communication ability to select males

Answer 64

Sperm whales - direction clicks that are repeated (usually in 3’s) called CODAS Different click types are used for echolocation as well as for attracting females, repelling males, and maintaining group cohesion Within the sperm whale head, the prominence equivalent to a melon in other toothed whales is hypertrophied (enlarged) & called the spermaceti organ. The spermaceti organ is enclosed in a case and filled with spermaceti oil, which is of a different composition than the melons of other toothed whales It is thought that the function of the spermaceti organ is to focus sound produced in the head of the animal.

Answer 65

Clupeidae is a family of ray-finned fishes, comprising, for instance, the herrings, shads, sardines Answer: 30%

Answer 66

Fish and shellfish provide -20% percent of the world animal protein consumption Marine fisheries -51% of fish protein Marine fish farms -13% of fish protein Freshwater fisheries -7% of fish protein Freshwater fish farms -29%of fish protein

Answer 67

The manager asks a fisheries scientist – who runs bioeconomic analysis e.g. will profitability increase if 20 large vessels are licensed to operate from a single port and subsidies to the existing fleet of smaller boats are scrapped * BUT larger vessels will provide fewer jobs than the numerous small boats that currently land catches in small harbours all along the coast – and representatives of fishing communities begin to lobby government * Government – concerned that conflict with fishers will result in bad publicity and jeopardize re election- decide to allow 20 larger vessels to enter the fishery – but also subsidizes fishing communities so small boats can keep fishing * The new policy is no longer based on the bioeconomic model but attempts to meet non –quantitative economic, social and political objectives * Result – too many vessels, chasing too few fish – overall profitability if fishery falls even further!

Answer 68

Catch controls: -Total allowable catches (TAC) -Individual quotas -Catch limits Effort controls: -Limited liscences -Effort quotas -Gear or vessel restriction Technical measures: -Size and sex selectivity -Time and area closures TAC – maximum quantity of fish that can be taken from specific stocks annually (every 2 years for deep sea stocks) IQ – Individual quotas - TAC divided between fishing units – sum of IQ =TAC Most quantitative fishery science is concerned with calculating the probability that a given outcome will result from given a management action Limited licenses - transferable IEQ - Individual effort quota Vessel/gear restrictions – size and power of vessels, amount, size and type of gear, how long can be left in the water

Answer 69

Management actions not always consistent (e.g. having a spatial closure but not limiting effort as in the Irish Sea cod recovery plan). Quotas / TACs are often exceeded and don’t account for discards or illegal landings. Effort control and technical measures are very effective but not used all the time – fishers don’t always want to limit catches! Managers too reliant on model outputs – trying to maximise catches as much as possible!

Answer 70

Fishermen have no direct control over the fish stocks that they are reliant upon. Fishing is very competitive and there are too many boats for too few fish (overcapacity) Hence fishermen have no incentive to limit catches and conserve the population.

Answer 71

Shared resource – fish know no borders * Brexit divorce - fish stocks like a joint bank account * Maximum sustainable yield - The principle of conserving fish stocks by only fishing as much as can be replaced each year - termed “maximum sustainable yield” - is enshrined in the EU’s Common Fisheries Policy and the UK Government has committed to upholding this principle post-Brexit. * The bank account- sustainable management means leaving the capital and only taking out the interest that is generated each year. * Great that the EU and UK agree on how much can be taken out - but the problem that arises is how that budget is shared.

Answer 72

Management actions are taken to meet a management objective – actions can be categorised as catch, effort, and technical measures – to work they have to be accepted and enforced * Catch controls that give fishers the rights to the resource, along with tech measures, are often the most effective * Stock assessments and the future are uncertain so a precautionary approach should be taken * Quantitative understanding of the responses to fishing is desirable because it allows managers to set strategies that are clearly understood

Answer 73

Likely to become an increasingly broad discipline and quantitative approaches to ecosystem analysis will become even more developed * Fishery managers are likely to be more concerned with economic and social issues and the conservation of non target species and habitats * In the future fishers may have to pay for access to the marine environment or to land catches * There are likely to be fewer fishers but their activities will be more profitable * New technologies are expected to improve enforcement and compliance * The international community must help people from less developed countries access alternative sources of food and income or we will see a growing gap between the sustainability, profitability and capacity for species and habitat conservation

Answer 74

* Short rigid body form (compared to other aquatic reptiles); low streamlined carapace * Limbs substantial modification - longer hind limbs (with more webbing) for thrust * In sea turtles – paddle like forelimbs have elongated phalanges embedded in connective tissue – no longer independent digits… tied to land due to reproductive behaviour

Answer 75

Magnetic field hypothesis 1. electromagnetic induction – assumes turtles have electroreceptors… never found 2. strength of the magnetic field affects the chemical reactions within the bodies of the newts and birds 3. magnetic crystals that form during the magnetic pulses from the earth's magnetic fields. These magnetic crystals formed by magnetite give the turtles directional information and guides in migration. The magnetite affects the cells of the nervous system of the sea turtle by producing a signal that references the forces of the magnetic field and the direction and magnitude that is applied. If this magnetite is used in the migration, when the earth's magnetic poles reverse at the dipole moment, the signal that the sea turtle nervous system receives will change the migration direction.

Answer 76

The ‘natal homing hypothesis’ Adults return to the beach they came from, often small isolated locations Chemical imprinting? (navigation) eg. follow strong signals in the sea Chemical imprinting? (recognition) eg. several experiments demonstrate that hatchlings exhibit a preference towards ‘’chemical cues’ that were present at the time of incubation Magnetic fields: “Sea turtle nesting density varies with slight changes in Earth’s magnetic field Results imply that sea turtles locate nesting beaches using geomagnetic cues”

Answer 77

Generic (PHASED) behaviour is exhibited by females at time of nesting: emerging from the sea preparing the nest site by digging a body pit (sometimes at multiple trial locations) digging egg chamber within the body pit - excavating flask shape hole with rear flippers in a scrape and flick motion depositing eggs within this chamber covering the eggs using rear flippers – filling in body pit camouflaging (arguable) the site by casting sand with all flippers returning to the sea - (exhausted) only to repeat 1-2 weeks later! Some species are a slight exception to the rule… all flippers used to excavate the body pit to lowers profile and identifies firmer sand to sustain the structure of the nest chamber

Answer 78

Sex determination - temp. warmer sand = more girls… * After hatching – may take 3-7 days to dig out… * Nest ‘explodes’ - Group “anti-predator role of within-nest emergence synchrony in sea turtle hatchlings” Santos. et al, 2016 – Proc. Roy. Soc. B. * typically at night * Dangerous migration to water * immediate wave orientation & frenzied flapping sex of most snakes and most lizards is determined by sex chromosomes at the time of fertilization, the sex of most turtles and all species of crocodilians is determined by the environment after fertilization. Six of the seven sea turtle species are currently listed as vulnerable, endangered, or critically endangered

Answer 79

Apply to pretty much every species BUT because of life history differences 1) Fishing: Long line in open ocean causes huge impact to pelagic phases (Leatherback decimated) Netting and trawling in coastal areas Remedies include: * pelagic fishing gear has attempted to move to paired trawl and gill nets and using nets that push out heavier things such as turtles. shrimp trawling industry to Turtle Excluder Devices by-catch of adults is now strongly regulated with strict zero tolerance policy for unattended nets (implementation of fines)

Answer 80

Development = pollution Wild animals eating turtle eggs Beach defences such as rocks Egg harvesting by humans and beatification of beaches such as flattening the sand. ------------------------------------------------ Remedies: ‘spreading the word’ to reduce pollution & disturbance Egg harvesting controlled (illegal or quotas). In many areas poachers are employed to protect beaches so reducing illegal harvesting pressure and increasing protection. Hatcheries may be established.

Answer 81

Despite the stated importance of marine mammals – very little is known about the abundance and population status of many marine mammal species (> 50 % unknown) Even where we do have some numbers the precision of these numbers varies greatly for the different species Commercial exploitation of cetaceans have significantly reduced many populations e.g. Balaenoptera musculus (blue whale) reduced from 200,000 – 14,000 due to commercial exploitation and southern right whales with reduced by as much as 90 % - now ~50% recovered. It is essential that we do know something about population status so we can implement relevant conservation strategies and understand the roles of marine mammals in the structure and function of marine ecosystems

Answer 82

Phocids (true/earless seals) appear to be more abundant than otariids (sea-lions and fur seals) - because phocids utilise highly productive environments in temperate and polar waters Estimated to be 19 separate populations of polar bears. Worldwide populations = 21,000 – 28,000 Passed near extinction of the sea otter but now populations increasing with more than 100,000 existing around the Pacific Rim and occupying > 75 % of their traditional habitats

Answer 83

Data sparse – no catch data! Deriving population level parameters based on individual level studies not ideal Mobility Caution Need for background knowledge on physiology, immune function, life history, ecology and behaviour Logistically difficult to develop and test speciﬁc threat mitigation measures.

Answer 84

Population census = total count; the total number of individuals within a population at a given time and place. Very difficult with few examples e.g. resident Orca’s off British Columbia Estimating abundance of a sample of a population = most common Population indices – the measure of a statistic which correlates with changing population abundance e.g. the number of Gray whales migrating up the Californian coast

Answer 85

Counts can be made or estimated in several different ways: Catch-effort analyses: not used much due to depletion of whaling Mark-recapture: commonly used esp. pinnipeds and baleen whales Strip-transect surveys: transect has a fixed width Line-transect surveys: infinite width Land-based visual surveys e.g. for coastal or land dependent species Acoustic surveys – mainly used for cetaceans

Answer 86

Populations - interbreeding group of individuals of the same species that exist in an isolated geographical area - probability of mating within significantly higher than between Some of the techniques used to examine population structure -Tagging studies and the analyses of morphometrics -DNA (mitochondrial and genomic) -Protein variations between populations -Stable isotopes Tagging studies include semi-permanent tagging e.g. radio-tagging and the use of natural markings e.g. fluke or dorsal fin Molecular biology has also led to novel analyses of social structure and behaviour Molecular biology also helped with field of population dynamics

Answer 87

Spatial instruments such as marine protected areas (MPAs) Mitigation measures for speciﬁc threats e.g. pinger deployment on gill nets Impact assessment on new constructions e.g. offshore wind farms Direct threat monitoring, e.g. using on-board observers or camera systems on ﬁshing vessels, acoustic monitoring around wind-farms, etc Environmental monitoring: surveillance of the structure, function and quality of supporting habitat of marine mammal species.

Answer 88

International protection = Broad, multi-species focus National / Local protection = Focused, species or area specific

Answer 89

Need to establish legally protected areas e.g. Special Areas at Sea (SAC) under the EU Habitat Directive Requires careful planning, clear objectives, and financial support SAC’s provides provisions to protect all cetaceans sand their habitat:- 1. Fishing activity e.g. control of bycatch 2. Pollution discharge 3. Industrial and recreational coastal development 4. Commercial boat traffic in sensitive areas Current legislation i.e. Wildlife and Countryside Act but now strengthened: £5,000 fine and up to 6 months in prison. Specific legislation required e.g. the UK Whale and Dolphin Act proposed by the WDCS. Would address:- 1. A ban on killing or wounding of cetaceans with a penalty for offenders (£5,000 - £20,000 & prison). 2. Complete ban of cetacean capture (up to £20,000). 3. Prohibition of disturbance and harassment (£5,000).

Answer 90

Although long lived = high fecundity, they can be low (akin to more K-selected) Therefore highly sensitive to environmental perturbations example: IWC in 1982 stated that the rate of increase of Sperm Whales to a population was about 0.01 individuals per year: Consider why evolutionary pressure for low fecundity e.g. Direct (care), indirect (social bonding) Example 0.02 and 0.05 seem to be representative of most dolphin species Maximum rates of increase of Dugong populations = 0.063 This however is not an easy parameter to get your head around so lets examine comparable doubling times e.g. rates of 0.02 = doubling time of 34.6 y and 0.15 = 4.6 y For marine mammal populations to be viable they must not fall below a critical threshold which is why the science of examining changes in population abundance over time is important The US Marine Mammal Protection Act (1972) designated this level as the Optimum Sustainable Population (OSP) level Difficult to determine without more studies both in number and rigour: Also should consider marine mammal populations to be resource dependent rather than density dependent = complex

Answer 91

CLASS: Reptilia ORDERS: Squamata Crocodilia Testudines Rhynchocephalia Squamata - comprising lizards, snakes and amphisbaenians (worm lizards Crocodilia- closest living relatives to birds Testudines - turtles, tortoises and terrapins. Rhynchocephalia- lizard-like reptiles that includes only one living species of tuatara (NZ – endemic)

Answer 92

Hydrophiidae (60+ sp.) True sea snakes Elapidae – Laticauda (genus) (6 sp.) Sea Kraits Also…Colubridae (12 sp.) and Acrochordidae (3 sp. file snake) Colubridae – largest snake family – every continent except Antarctica – Acrochordus granulatus - It is completely aquatic and almost helpless on land – SE Asia none of these are territorial and don't really have a home.

Answer 93

1. Highly developed visual and olfactory senses. Jacobson's (vomeronasal, VNO) organ. auxiliary olfactory sense organ used to sense prey ESP.UNDERWATER; sends neuronal signals to the hypothalamus and not accessory olfactory bulb- may influence aggressive and mating behaviour. As it is easier for a snake's tongue to fulfill its olfactory function under water, its action is short compared to that of terrestrial snake species. Only the forked tips protrude from the mouth through a divided notch in the middle of the rostral scale 2. have a squished end tail that resembles a keel to help locomotion in the water. Moreover, the tail is also photosensitive meaning the snake can tell when their tail is out in the open, allowing them to move their tail out of the way of predators.

Answer 94

1. small scale organs - termed ‘scale sensilla,’ in fully-marine Aipysurus duboisii (top) and a close terrestrial relative Pseudonaja textilis (bottom) These scale organs are presumptive scale sensilla that purportedly function as both tactile mechanoreceptors and potentially as hydrodynamic receptors capable of sensing the displacement of water scale sensilla are more protruding (dome-shaped) in aquatic species than in their terrestrial counterparts. Second, exceptionally high overall coverage of sensilla is found only in the fully aquatic sea snakes. 2. salt removal: The posterior sublingual gland of sea snakes is a salt gland. It secretes a fluid surpassing seawater in sodium chloride concentration. The gland lies on the ventrolateral surfaces of the tongue sheath and empties through multiple ducts into the sheath. Fluid is expelled from the sheath when the tongue is extended.

Answer 95

1. Deep recesses between scales (‘hinge’) entrap and wick water over the body surface - keep skin wet when floating? non-overlapping, polygonal knobs with flattened outer surfaces bearing presumptive filamentous sensillae The deep recesses between scales (‘hinge’) entrap and wick water over the body surface - possibly serves to maintain the skin wet when the dorsal body protrudes above water while floating on calm oceanic slicks where they forage outer keratin level thinner = improved respiratory gas exchange in skin. kin also includes filamentous receptors that permit nearby prey detection and even help distinguish freshwater from seawater. 2. Diving: nostrils have valves that consist of a specialised spongy tissue to keep water out; windpipe can be drawn up to where the short nasal passage opens into the roof of the mouth (snorkel) The lung has become very large and extends along most of the body = buoyancy and storing air for dives. ↑ SA:vol (↓ vol:SA) = efficient exchange In general are able to (a) respire through their skin (unusual since skin is thick and scaly) (b) squeeze lungs

Answer 96

Cannot maintain body temp above that of surroundings; therefore demand for O2 lower Aerobic = liberate ATP, CO2 and heat v anaerobic (lactic acid and O2 debt). Typically never fall into anaerobic situation Cardiac ‘shunts’ – change relative pressure between L and R + resistances to regulate flow to body v pulmonary demand = allows fine tuning Special valve connecting artery and vein entering lung so can by pass or close off (pulmonary shunt) Cardiac shunts – “three chambered” heart - the blood leaving the heart for the body is only partially aerated; part of it is made up of deoxygenated blood returned from the body.

Answer 97

Sexual dimorphism (H: F>M whilst E: F< or > sp.-specific) E is less adapted to marine life (retains the wide ventral scales typical of terrestrial snakes and has only a poorly developed tail fin) ventral scales, or gastrosteges, are the enlarged scales that extend down the underside of the body Reproductive mode *except Laticauda Ovoviviparous (Kraits only)* Common sea snake is viviparous Despite this both have similar clutch sizes

Answer 98

Use visual cues (including size, movement and color pattern) to assess whether snake-shaped objects are potential partners! Skin lipids (pheromones – produced by females) are important only after the male comes into physical contact Visual cues provide unreliable information …Generally inefficient at finding a mate unless short distances Sea kraits – pheromones act to stop in-breeding between closely related species

Answer 99

Foraging and prey capture – mostly by smell and vibration Crevice – protruding tongue against substrate as explores cryptic envs; eat prey immediately or retreat & wait Near-bottom cruising – intercept fish with a lateral strike by rapidly swinging head sideways. Common to miss! Ambush – Yellow-bellied only Browsing – Emydocephalus annulatus only with expanded scale on uper jaw to scrape eggs from Damselfish broods

Answer 100

Threats – little is known 1. being eaten by people and commercial trawl fishing + as bycatch Boat strikes Pollution harvesting for clothing

Answer 101

Hard to conserve them because people don't think snakes are important and are afraid of them. Establishing marine protected areas (yet not enough still known about inter-exchange of populations) The introduction of by-catch reduction devices, such as square mesh and fisheye windows. Knowledge gap: “miss information on breeding cycles, by-catch and mortality, growth rates, population density, sexual maturity and taxonomy in most areas” Major considerations: * High site fidelity means localised impacts and difficulties with re-introduction programmes; low incentive for protection? * Surprisingly few species even listed as threatened – none on CITES

Answer 102

Two species considered ‘marine’: American crocodile (Crocodylus acutus) Saltwater crocodile (Crocodylus porosus)

Answer 103

* Pitted appearance of the skull (fusion of skin) * eyes, ears, and nostrils are located on the same plane on the top of the head (great for predation) Squat-legged quadraped * Skin is formed from a thick dermal layer covered with non-overlapping epidermal scales. Rows of ossified scutes, osteoderms, along back and tail (scales of each scute slough off individually rather than shedding in large patches) * salt excretion by glands on the tongue

Answer 104

Two primary modes of locomotion on land: “belly crawl” and “high walk” (some gallop at alarmingly fast speeds) * swim by moving their body and tail in a sinuous fashion (but cannot speed for long Swimming aided by partially webbed feet Don’t forget, they can also ‘jump’ – propelling vertically from water

Answer 105

Nictitating membranes – transparent third eyelid Ears (located behind the eyes) close exhales air to drop under the surface (controlled descent) stones swallowed (known as "gastroliths") add weight and act as a ballast. Palatal valve reveal the opening to the trachea (the 'glottis'). When sealed, neither water nor air can enter the throat from the mouth Under (a 'minimum exposure profile') still needs to breath (eyes and nostrils exposed uses internal nares (where the nostrils open internally) to move to the back of the upper palate. Here, by-pass the palatal valve and breathe. When the crocodile's head is totally submerged, however, the nostrils are sealed to prevent influx of water

Answer 106

Extremely good BUT not visual underwater (sealed eyes and ears) 'integumentary sense organs' (ISOs) = sensory cells in the integumentary layer (skin). ISO - densely distributed on the jaws of crocodilians Found in various locations of body so function debated, likely: JAWS = directional mechanoreceptors to detect pressure changes (prey nearby) Despite crocodilians' armoured bodies, the ISOs imparted a mechanical sensitivity exceeding that of primate fingertips” “ISOs have diverse functions, including detection of water movements, indicating when to bite based on direct contact of pursued prey, and fine tactile discrimination of items held in the jaws.”

Answer 107

As with sea snakes have a four-chambered heart efficient at oxygenating their blood 60% of fat in crocodile diets is stored. The trade-off is a low oxygen count in the blood (it can also impair growth). Crocodiles recover slowly from exercise and are easily exhausted; have high levels of lactic acid in the blood Typically loiters in the water or basks in the sun preferring to hunt at night. Capable of explosive bursts of speed when launching an attack (land or water)

Answer 108

circulatory system can divert blood away from the peripheral systems during dives or to reduce heat loss strong muscles allow jaws to snap shut but muscles for opening the jaw are relatively weak Juveniles feed on insects, crustaceans, small reptiles, frogs, and small fish. More mature, larger crocs eat turtles, goannas, snakes, birds, livestock (cows), buffalo, monkeys, wild boar, and mudcrabs

Answer 109

reach sexual maturity at 10-12 yr (F) & 16 yr (M) * courtship consists of a complex sequence of behaviors which may last for several days * attracting mate – males initiate with ‘head slaps’; interest females initiate submissive ‘head lift’ Nest building occurs in well-drained soil adjacent to water prevents flooding & allows direct access to water * lays all her eggs (40) during a single night * cover eggs to protect from desiccation and predators such as raccoons * returns to open the nest (90 days), and may carry the hatchlings to the water/ assist hatchlings by cracking shells with her jaws

Answer 110

Most commonly grey to black with pyramid-shaped dorsal scales * Shorter more blunt snouts than land iguanas * Slightly laterally compressed tail and swim by lateral undulation of their bodies with limbs held to the side * Claws are long and sharp to enable grip in the dynamic intertidal

Answer 111

Seven subspecies of endemic marine iguanas are found throughout the islands. Differ in size between islands, from 75 centimeters (Genovesa) to 1.3 meters (Fernandina, Northern Isabela) in length Espanola boasts the most differentiated and colorful iguanas (blotches of coppery green and red). Red comes from a rhodophyte sp. that blooms during the summer when iguanas are mating

Answer 112

Diet – exclusively on algae Amblyrhynchus, (amblys = short, rhynchos = nose) is derived from the blunt snout, which allows them to efficiently scrape algae off of the rocks with their sharp three-cusped teeth Larger members of the species feed more often by diving at high tide while smaller animals are restricted to intertidal feeding at low tide Salt excretion - A gland connected to the nostrils (between the eyes) removes salt from the body: concentrated and sneezed out

Answer 113

Metabolism – Ocean waters are cold and so must bask. At low temperatures cannot move effectively so are highly aggressive (relying on less energetically expensive bluffs or bites than escape) Diving – as for crocs; iguanas can remain submerged for up to an hour, (dives of 5 to 10 minutes are more common). Can perform cardiac shunts

Answer 114

Large males assemble "harems" of several females * head bobbing major display to other males (and humans!) * Fights occasionally occur - heads together & push opponent backward. Females lay 1-6 eggs in burrows 30- 80 cm deep. * The eggs are laid in sand or volcanic ash up to 300m or more inland. * Females defend nests for first few days & then leave the eggs to incubate (95 days).

Answer 115

A major change in the marine algal flora November 1982 - July 1983: high rainfall, sea level, and sea surface temperatures caused a decrease in biological productivity, survival and reproduction. During El Niño conditions when algae decreased for two years, some were found to decrease their length by as much as 20%. When food conditions returned to normal, the iguanas returned to their pre-famine size. It is speculated that the bones of the iguanas actually shorten as a shrinkage of connective tissue could only account for a 10% length change”

Marine Vertebrates Flashcards

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