What is the sister group to all animals?
Choanoflagellates
Protists are considered to be _____
Animals
Dr. Schaffer doesn’t think sponges have _____ tissues
Epithelial tissues
What type of branching sequence leades to sponges and Coelenterates on the Molecular-Based Phylogeny of Animalia?
Polytomies
What are Polytomies?
Polytomies are unresolved branching sequences
What is a blind gut?
having one opening for the mouth and anus
Explain the relationship with humans being bilateral and having cephalization?
This goes together because we have all of our sense organs at the top near or in our head.
What are the characteristics of animals?
- Multicellularity
- Differentiated cells, tissures, organs
- Motility at some stage
- Heterotrophy
- Muscular and neurosensory system
- Complex development including blastula formation (all) and gastrulation (most)
Define Metazoa
All animals
Define Eumetazoa
All animals excluding sponges and a few others
Characteristics of Eumetazoa
- Two or three cell layers
- Radial or bilateral symmetry
Define bilateria
All animals excluding sponges, cnidaria and a few others
Characteristics of bilateria
- Three cell layers
- Bilateral symmetry (ex. echinoderms)
What are common evolutionary trends in animals?
- Increasing size and morphological complexity
- Exploitation of new (benthic/terrestrial) enviornments
- Homeostasis
- Increasing nervous system
Homeostasis in animals is the increasing ability to…
- Perceive, respond to and control conditions of life
- Maintain constant internal conditions in the face of external enviornmental fluctuations
Three things the nervouse system in animals has increased by
- Nervous system complexity. Nerve nets replaces by central nervous system
- Cerphalization: concentration of sense organs at the front of the animals (often paired with bilateral symmetry)
- Intelligence: Behavior; social interaction; cognitive ability; self-awareness
Define nerve net vs. central nervous system
Nerve net: diffuse neurons in hydra
Central nervous system: clustered neurons in earthworms
Three principle animalia groups
- Porifera (sponges)
- Cnidaria (hydra, jellyfish, corals)
- Bilateria
Characteristics of porifera (sponges)
- Radial symmetry or no symmetry
- No cell layers as such
Characteristics of cnidaria (hydra, jellyfish, corals)
- Radial symmetry
- Two cell layers
Characteristics of bilateria
- Bilateral symmetry
- Three cell layers
Three major bilaterian groups
- Lophotrochozoans
- Ecdysozoans
- Deuterostomes
What do lophotrochozoans include?
- Mollusks - snails, clams, cephalopods
- Annelids - segmented worms
What do ecdysozoans include?
- “Molting animals”
- Arthropods and their allies
What do deuterostomes include?
- Echinoderms - starfish, etc.
- Chordates - “fish”, tetrapods
How are phyla distinquished base on their body plans?
- Symmetry
- Number of embryonic cell (tissue) layers
- Embryonic cell layers
- Types of body cavities
- Embryonic development
What are the three types for animal symmetry?
- Radial
- Bilateral
- Other
Define diploblastic
Having two tissue layers of embryonic cell
Define triploblastic
Three tissue layers of embryonic cells
Define one embryonic cell layer: endoderm
Mucous membranes lining digestive tract and respiratory system
Define one embryonic cell layer: Mesoderm
Muscles, bone, blood, and other connective tissue
Define one embryonic cell layer: Ectoderm
Skin (epidermis), nervous system
What are the three types of body cavities?
- None
- Pseudocoelom
- True coelom
What kind of body cavity does acoelomates have?
Acoelomates have no enclosed body cavity
What kind of body cavity do pseudocoelomates have?
Pseudocoelomates have an enclosed body cavity partially lined with mesoderm
What type of body cavity do coelomates have?
Coelomates have an enclosed body cavity completely lined with mesoderm
What is the pseudocoelonate round worm/nematode feature that allows for locomotion?
Hydrostatic skeleton with a body wall lined with muscles
How do pseudocoelomate round worms move?
Round worms move by muscle contractions moving fluid around which changes the shape of the animal
What is the coelomate earthworm body plan?
The tube-within-a-tube body plan
Two types of embryonic development
- Protostomes
- Deuterostomes
Features of protostomes
- Blastopore becomes the mouth (some protosomes have both their mouth and anus form from the blastopore)
- Coelom (body cavity) forms within mesoderm
- Cleavage spiral in some
- Embryonic cell fate determined early
Features of Deuterostomes
- Blastopore becomes the anus
- Coelom forms from an out-pocketing of the gut
- Cleavage radial
- Embryonic cell fate determined late
Picture of difference between development in protosomes and deuterostomes
What is the traditional view regarding the origin of embryonic tissue types
Germ layers and gastrulation evolved after sponges
What is the more modern suggestion about the origin of embryonic tissue types
- Beginnings of germ layer differentiation seen in some sponges (not after like in traditional view)
- Based on observation in sponges of a transcription factor important in regulating endodermal development in Eumetazoa
What are antigenic properties of adult tissues in humans determined by?
By embryonic tissue of origin
What is Steven Johnson Syndrome (SJS) an example of?
Autoimmune disease based on antigenic properties of adult tissue determined by embryonic tissue of origin
Features of the often fatal Steven Johnson Syndrome (SJS)
- Auto-immune disorder triggered by drugs and infection
- Antibodies attack epithelial tissue (skin, cornea, etc.) i.e. tissue that derives from ectoderm
- Skin dies, sloughs off
- Dermis largely unaffected-antigenically distinct; derives from mesoderm
- Sequelae include permanent damage to eye
- But-if patient survives, essentially normal skin often replaces tissue that was lost
How do filter feeders eat?
They eat by…
- straining out food particles
They are…
- Clams; krill (crustaceans); baleen whales
How do Deposit feeders eat?
They eat by…
- Eating their way through the environment
They are…
- Earthworms
How do fluid feeders eat?
They eat by…
- suckers and drinkers
They are…
- Hummingbirds, adult mosquitoes, vampire bats
How do mass feeders eat?
They eat by…
- Biting and tearing off chunks
They are…
- Us :/
What do predators eat?
Eat other animals
What do herbivores eat?
Plants
What do detritivores/saprovores eat?
Dead/decomposing matter
What do omnivores eat?
Anything
What prefix do parasites that live in a living host have?
endo-
What prefix do parasites that live on a living host have?
ecto-
What is the taxanomic group for this deposit feeder: Earthworms
Annelida
What is the taxanomic group for this deposit feeder: Sea Cucumbers
Echinodermata
What is the taxanomic group for this filter feeder: Krill
Arthropoda
What is the taxanomic group for this filter feeder: Baleen Whales
Chordata
What is the taxonomic group for this fluid feeder: Butterflies
Arthropoda
What is the taxonomic group for this fluid feeder: Blowflies
Arthropoda
What is the taxonomic group for this mass feeder: Horses
Chordata
What is the taxonomic group for this mass feeder: Snails
Mollusca
Undulate
Move in a smooth constant motion like slitering
Three examples of whole body undulates
Nematodes, fish, snakes
What do nematodes use to move?
Muscles and pseudocoelom
What do fish and snakes use to move?
Muscles and skeleton
Types of limbs for walking, paddling, and flying
- Sac-like
- Tube feet
- Jointed (external skeleton)
- Not jointed (internal skeleton)
Example of organism with sac-like limbs
Onycophorans (looks like a huge, swollen centipede)
Example of an organism with tube feet for limbs
Echinoderms (starfish!!!)
Example of organisms with jointed (external skeleton) limbs
Arthropods (insects, crustaceans, spiders)
Example of organisms with non jointed (internal skeleton) limbs
Vertebrates (mammals)
T or F: Animal limbs are homologous
FALSE; Often limb development controlled by same genes, however, limbs themselves arose independently. This means that the GENES ARE HOMOLOGOUS NOT THE STRUCTURES
Schaffers way of remembering that animals limbs are not homologous
Teenagers all race down to the car shop and they all get the same parts for their cars but they all do something unique and different with these parts even though they got them from the same place
What is DII in a phylogenetic tree?
DII is distulis which means limbs
Which group of animals (metazoa, eumetazoa, or bilateria) has a possible phylogeny of genes that control limb development and other functions shown up in?
Bilateria
What are urochordate ampullae?
Blood filled sacs that mediate an immune response when colonial tunicates come into contact
What was the point of the gene DII experiment that involved limb formation in species other than insects?
Dye connects to limb development genes and they can see where the genes are shown after the embryonic phase
Define ampheoxous
Argues that all animals have appendages that are homologous
Define parapodia
Sort of legs more non jointed
Sea urchins (echinodermata) have ____
Tube feet
Pick one: animal life cycles are all haplontic/diplontic with a few interesting exceptions
Diplontic (diploid except for gametes)
What do multiple stages of the animal life cycle facilitate?
- Dispersal
- Exploitation of different environments, resources
T or F: Stages can be represented by different individuals or the same individuals or the same individual
True
Is animal reproduction sexual or asexual
Both asexual and sexual
Is animal fertilization internal or external
Either
Is animal birth live or from eggs?
Either
What is holometabolous metamorphosis?
Complete metamorphosis which consists of four stages: egg, larva, pupa, and adult.
What is hemimetabolous metamorphosis?
Incomplete metamorphosis which consists of three stages: egg, nymph, and adult.
Main difference between incomplete and complete metamorphosis
Complete metamorphosis consists of a very active, ravenously eating larva and an inactive pupa whereas incomplete metamorphosis consists of a nymph, which resembles a miniature adult
How do baby mosquitos breathe?
Wriglers connect breathing tubes to the air and filter feed and breathe in water
Explain the life cycle of a broad fish tapeworm
- Eggs are in a lake
- Theyre just developing in their first larval stage
- A copepod crustacean comes and eats the larva (first intermediate host) in the second larval stage
- Then the small fish eats the copepod in the third larval stage
- Then the big fish eats the small fish in the third larval stage
- Then bears or humans eat raw big fish and get infected with tapeworm
Why does the broad fish tapeworm need and have so many hosts?
The broad fish tapeworm needs multiple hosts because the bigger ones are able to provide more resources and better chances of reproduction as bugger hosts have more room and resources for more eggs than the smaller fish and even smaller copepod
What type of group are sponges?
Not monophyletic
Characteristics of sponges
- Radial symmetry or asymmetry
- Sessile
- Has water canals (pores)
- Has specialized collar cells (choanocytes)
What kind of symmetry do sponges have?
Radial symmetry or asymmetrical
What does sessile mean?
Support provided by a “skeleton” consisting if spines called spicules and or an elastic networ of fibers
What do sponge’s specialized collar cells (choanocytes) do?
- Suck water in
- Extract food particles
- Excrete waste products
Where does water exit?
“used” water exits through one or more oscula
How is good water and bad water mediated in sponges?
Good water with food is sucked in by the beating of the flagella and bad water is pushed out
What are organisms under the phylum of cnidaria?
- Hydras
- Jellyfish
- Corals
Characteristics of cnidarias (hydras, jellyfish, corals)
- Two cell layers
- Radial symmetry
- “Blind” guts
- Almost all marine
- Carnivorous
- Three principal groups (Hydrozoans, scyphozoans, anthozoans)
What is the basic structure of cnidarias?
Two-layered, tentacle bearing cup that is either a polyp (sessile) or a medusa (floating)
What doe the cnidaria life cycle include?
- Polyps reproduced by budding
- Meduses reproduce sexually
- Fertilized eggs develop into ciliated free-swimming planula larva
Name the three principal groups of cnidaria
- Hydrozoans - hydras (solitary and colonial)
- Scyphozoans - jellyfish
- Anthozoans - anemones (solitary); corals (colonial)
What is the Portugese man-of-war
- Physalia physalis
- Floating hydrozoan colony
- Consists of diffferentiated polyps specialized for different functions: floating (“sail” - gas filled float), stinging, feeding and reproduction
- Tentacles pack a wallop
- NOT A JELLYFISH
Characteristics of corals
- Famous for reef formation
- Many contain symbiotic photosynthetic dinoflagellates
- Anthozoans
What was Darwin’s first book on?
Coral
Since corals have reef formations and symbiotic photosynthetic dinoflagellates they…
- Have the ability to live in nutrient poor waters
- Have restriction to surface waters
Why do corals live in shallow water?
Because they have algae that lives in them that needs to do photosynthesis
Are coral reefs often found far out in the sea?
Yes; they are often found far out to sea where they form ring-like atolls around shallow lagoons
- Adjacent water is very deep
What is Darwin’s conjectured solution about atolls?
Darwin proposed that atolls formed by a balance between sea floor subsidence and reef growth
What is Charles Lyell’s thought about corals?
Charles lyell thought that these corals were living on the rims of volcanos
What ended the different ideas of the corals?
Hydrogen bombs ended these ideas; Scientists came in before the bomb ecploded and they checked to see how far down the reef would go and the scientists found that the corals have been growing since the Eocene
Characteristics of ctenophora (comb jellies)
- Name derives from locomotor organ consisting of eight comb-like rows of fused plates of cilia called ctenes
- Previously grouped with Cnidaria in Coelenterata
- Complete gut
- Two cell layers separated by gelatinous meoglea
- Tentacles, but no nematocysts - use sticky filaments
What are ctenes?
Locomotor organ consisting of eight comb-like rows of fused plates of cilia. They dont sting they get prey by attaching to them.
What taxa do protostomes and deuterostomes split up?
Bilateria
What are the similarities between protostomes and deuterostomes?
- Triploblastic (three cell layers)
- Have free-floating, ciliated larvae (dispersal stage) that differ with regard to number and anatomy of cilia
What makes protostome and deuterostome larvae different?
The number and anatomy of cilia
What are two groups of protostomes?
- Lophotrochozoa
- Ecdysozoa
What types of organisms do lophotrochozoa include?
- Flatworms
- Rotifers
- Lophophorates (Bryozoans, brachiopods, phoronid worms)
- Spiraliabs (Nemertean worms, annelids, mollusks)
Where does the word lophotrochozoa derive from?
Derives from lophophore (a feeding organ) and trochophore larva
- The word lophophore from the greek - lophos = ‘crest of a helmet’ + phoros = ‘bearing.’ hence, ‘crest-bearing’
- U-shaped ridges around the mouth bear one or two rows of hollow, ciliated tentacles - videos
- Occur in lophotrochozoan groups that collectively from the lophophorates
T or F: All lophotrochozoans have lophophores (feeding organ)
False; Not all have lophophores
If there is skeleton or shell in a lophotrochozoa, how do they grow?
They grow by accretion which is basically addition
What are todays most important cephalopods without shells?
Octopi
How do lophophores work?
They extend their lophophores our of their body and the lophophore spreads out, the lophophore begins to rock and rotate and goes back and forth to collect as many particles as possible. The lophophore begins to retract into the gut.
What does the taxa Ecdysozoa consist of?
“Worms”
Lobopods
Arthropods
How do ecdysozoa grow?
Grow by molting a stiff external skeleton
How do ecdysozoa (worms, lobopods, arthropods) move?
Locomotion often by jointed appendages
What is ecdysozoan phylogeny based on?
Molecular data and evidence (small ribosomal subunit and other genes)
Difference between Ecdysozoa and Lophotrochozoan growth
Lophotrochozoans have a shell that is either open at one side or both so it can grow by accretion where as the ecdysozoa has an exoskeleton so it has to molt
What group of organisms have the most advanced ecdysozoan skeletons?
Athropods; they are essentially suits of armor
Explain the anatomy of the arthropod exoskeletons
Consists of plates joined by aticular membranes; secreted by underlying hypodermis
Explain how an arthropod molts
- At molting, the hypodermis secretes an enzyme that erodes the base of the overlying cuticle; new cuticle forms beneath it
- The old cuticle splits, and the animal crawls out
- New cuticle soft, pliable - allows animals to grow
- Growth stage between molts called instars. Metabolic reserves accumulate between molts
What do Uniramians include?
Includes insects (three body regions, three pairs of legs attached to the thorax)
Body plan of uniramian insects
Three body regions, three pairs of legs attached to the thorax
What was the most successful phyla in the metazoa phyla?
Uniramians; many also have wings
What is an advanced trait of the uniramians?
They have the ability to maintain constant body temperature- some moths and bees
Where do honey bees maintain their constant body temperature?
Honey bees maintain their constant body temperature in their thorax
What is the Wings from legs theory?
Ancestors of winged insects may have had a tiny premature wing on their leg resulting in a small pleura (space between wing and leg)
What is the wings from tergal extensions theory?
The ancestor of winged insects may have had a premature wing on its actual body resulting in a close to full grown pleura (space between wing and leg).
Who were the competing hypotheses for the evolutionary origin of wings from?
Jockush and ober (2004)
What is the significance of where the ancestor wing in the competing hypotheses started out?
It may have supported gills with the wings sprouting out from the leg
What are the social hymenoptera in the uniramians?
ants, wasps, bees
Why are ants, wasps, and bees social hymenoptera?
They have complex societies with individuals specialized behaviorally and morphologically for different task. They also have sterile workers
Are social hymenoptera males haploid or diploid?
Haploid; they are more closely related to their sister than they are to their daughter
What do the explanations for why social hymenoptera workers are sterile?
- Haplodiploid sex determination (males haploid; females diploid)
- Kin selection
Referring to the cladogram on page 1 and with regard to mono- / polyphyly, vertebrates are a __________ group; invertebrates are ____________.
Referring to the cladogram on page 1 and with regard to mono- / polyphyly, vertebrates are a monophyletic group; invertebrates are parayphyletc.
Referring to the cladogram on page 1, which of the fol- lowing traits arose just once?
- Coelom
- Limbs
- Pseudocoelom
- Radial symmetry
- Segmentation
Coelom
Referring to the cladogram on page 1, the acoelomate condition of flatworms is a(n) _________ trait.
Referring to the cladogram on page 1, the acoelomate condition of flatworms is a(n) derived trait.
The mass of cells that results from division of the original fertilized egg is called a blastula. A ______ results when the blastula invaginates.
The mass of cells that results from division of the original fertilized egg is called a blastula. A gastrula results when the blastula invaginates.
If all animal limbs really are homologous (as opposed to the genes that control their development), cephalochor- date ancestors must have ___________________.
If all animal limbs really are homologous (as opposed to the genes that control their development), cephalochor- date ancestors must have lost their limbs.
SJS patients often require intubation. Why? (You may have to look up “intubation.”)
The lining of the throat derives from embryonic ectoderm. It becomes inflamed, swells and the patient is unable to breathe unassisted. Hence the need for a breathing tube.
A general evolutionary trend among animals has been increased size and complexity. What would Lamarck have had to say about this? What would Darwin have said? Be brief. (Not covered in lecture)
Lamarck would have approved, citing the Power of Life. Darwin would have suggested that, while great- er complexity is often favored by natural selection, there are many cases in which it is not.
Baleen whales are huge; their prey, tiny. Most predators that eat small prey are themselves small. Why?
The smaller your prey relative to your needs, the more you have to catch and eat. Crudely, and absent some sort of efficient sieving device, you want to eat the largest prey you can handle.
Strategies that have been employed in the fight against malaria include the following:
a. insecticides;
b. draining ponds and marshes;
c. anti-malarial drugs;
d. window screens;
e. bed nets often impregnated with insecticide.
Which of these target(s) the larval stage?
a. if the target is bodies of water; b.
The classifications / phylogenies given in this lecture are quite different from those that your instructor learned way back when. What principal development(s) might have caused the changes?
a. Advent of molecular- based phylogenies.
b. Adoption of cladistic method- ology.
In many social hymenoptera (ants, bees), workers (all diploid females) are generally sterile. In these species, males are haploid. From an evolutionary point of view, how might these observations be related? (Requires outside reading.)
Imagine for argument’s sake that the species in question has a single pair of chromosomes. Call Dad’s single chromosome XM, and call Mom’s two chromosomes XF1 and XF2. Females, all sisters, have two chromosomes, and their genotypes will either be XMXF1 or XMXF2. If we average over many females, the average number of genes any two will have in common is 75%, i.e., they all get Dad’s chromosome and there is a 50% chance that they get the same chromosome from Mom. By way of contrast, females only have 50% of their genes in common with their own female offspring, to which they and the male with which they mate each contribute a single chromosome. New queens are their sisters – this is critical. So the workers should forego reproduction in favor of feeding the existing queen and nurturing her female offspring, some of which will become new queens.
Regarding your answer to #11, how would your answer be affected by the observation that queens often mate with multiple males? Likewise, how does sex determina- tion in termites affect your argument? (Requires outside reading.)
Queens store sperm in a special structure called a spermatheca. If Mom mates more than once, her reproductive offspring may not be your full sister. Termite males are diploid, so the argument given in the answer to Question 12 doesn’t apply. Nonetheless, termite colonies are organized in much the same way as the nests of social hymenoptera, i.e., only the queen lays eggs. From this, we conclude that haplodiploidy may be sufficient to for the evolu- tion of sterile workers, but it is not necessary.
In fact, not all hymenoptera are social, this despite the fact that all hymenoptera have haplodiploidy sex determination. It follows that haplodiploidy isn’t sufficient for the evolution of worker sterility either. What one is left with is the weaker, and far less satisfactory, assertion that haplodiploidy appears to increase the likelihood that sociality and worker sterility evolve.
What do deuterstomes include?
Echinoderms and chordates
Characteristics of echinoderms
- Pentameral (5-way) symmetry
- Marine
- Includes sea lilies (crinoids - mostly extinct), sand dollars, sea urchins, starfish
- Deuterostomes
Characteristics of hemichordates
- Pterobranch and acorn worms
- Former traditionally in a separate group
- Deuterstome
Three types or chordata
- Urochordates
- Cephalochordates
- Vertebrates
What do urochordates include?
Tunicates, sea squirts
What do cephalochordates include?
Lancelets
What do vertebrates include (under chordata)?
Jawless fish, sharks, rays, bony fish, tetrapods
What could the possibilites of origin for deuterstomes be?
Fossil of Yunanozoa found in china that was originally considered to be a basal deuterstome but now hemichordate
Possibly a living xenoturbella
Characteristics of xenotrubella: the possible origin of deuterostomes
- Small, worm-like, acoelomate
- Suggested affinities include:
- Degenterate mollusk - more likely a mollusk predator, i.e., mollusk genes came from its food
- Basal bilaterian related to Acoel flatworms
- A 4th deuterstome phylum most closely related to echinoderms and hemichordates
What is the sister group to Xenoturbellida?
Echinodermata and Hemichordata
What is the sister group to Chordada?
Echinodermata, Hemichordata, and Xenoturbellida
What are Echinodermata and Hemichordata called?
Their node is called ambulacraria
What type of skeletons do echinoderms have?
Internal skeletons composed of calcareous plates lying just below the skin and supercificial musculature
What leads to the extensions in echinoderms called tube feet?
Water vascular systems composed of calcified, hydraulic canals
What do the tube feet in echinoderms function in?
- Gas exchange
- Locomotion
- Feeding
What type of symmetry do echinoderms have?
Five-way symmetry a derived character as evidenced by larval bilateral symmetry
- In some sea urchins, five-fold symmetry in the adult is replaced by partial secondary bilateral symmetry- adaptation for burrowing
What do Hemichordates (part of the deuterstome phyla) use pharyngeal gill slits for?
Gas exchange and or filter feeding (recent studies suggest alternation between filter and deposit feeding)
General body plan for deuterstome hemichordates:
Three parts: Proboscis, collar, trunk
Acorn body plan (a hemichordate part of the deuterstome phylogeny)
Proboscis: Mucous covered burrowing organ; food capture
Collar contains mouth
Trunk contains numerous pharyngeal gill slits
Pterobranchs body plan in relation to acorn worms (hemichordate deuterstomes)
Proboscis reduced
Collar bears tentacles
Gill slits reduced in number or absent
How many different groups do hemichordates have?
Two; Acorn worms and pterobranchs
Why are hemichordates covered in mucus?
Used for catching food and burrowing
What do chordates and hemichordates have in common?
They both have pharyngeal gill slits
List the 4 chordate synapomorphies
- Hollow, dorsal nerve cord
- Dorsal supporting rod, the notochord
- Muscled tail that extends beyond the anus
- Endostyle or thyroid gland derived therefrom
Do humans have a dorsal supporting rod like chordates?
Humans dont have a dorsal supporting rod but it begins to develop when we are an embryo then it gets resorbed
What are chordate (deuterostome) gill slits specialized for?
Gill slits specialized for filter-feeding
What are the three subphyla underneath chordates?
- Urochordata
- Cephalochordata
- Vertebrata
What does tunicates mean?
Tunicates means that Urochordates have an outer coverung that can be flexible
Characteristics of urochordates (tunicates)
- Marine and mostly sessile (They just sit there in their adult phase)
- Adult pharynx expanded into gill basket - traps food particles with muscous secreted by the endostyle
- Motile larva with notocord, dorsal nerve cord and tail that are resorbed during metamorphosis in most
Explain how food passes in and out of the gill baskets of urochordates
Water comes in and the food passes through the gill basket that is covered in muscous that is secreted by the endostyle and the mucous carries the food into the stomach
Explain tunicate metamorphosis
Free-swimming larva attache to the substrate with “adhesive organ” then the swimming parts essentially stop functioning and the inner organs particularly the gill basket which strains food from the water, expands
Cephalochordate (lancelets) similarities with vertebrates
- Segmented muscles
- Notochord
- Dorsal nerve chord
- Pharynx
- Gills and gill slits
- Post-anal tail
Cephalochordate and vertebrate differences
Cephalochordates have…
- No skeleton
- No paired appendages
How do cephalochrodates breathe and eat?
breathe through their skin (like frogs) and gills are used for feeding
T or F: Despite fusiform shape, lancelets are sedentary
True; lanceletes (cephalochordate deuterstomes) are sedentary which means they are very inactive
When are Amphioxous-life fossils from:?
Mid-cambrian
In _____ both the gonads and nephridia are segmental
Amphioxus; this sets them apart from other vertebrates
What are two vertebrate (deuterstomes) synapomorphies?
- Vertebral column
- Skull enclosing a hollow brain
What were archetypal vertebrate like?
Free-swimming and fish-like
How do vertebrates move?
Motion accomplished by contraction of segmented, vee-shaped trunk muscless (tips pointed forward)
Explain the anatomy of the vertebrate (deuterostome) trunk muscles
- Muscles arranged in dorsal and ventral bundles called myomeres one of each per vertebra
- Attach to vertebral column via sheets of tendon-like connective tissue
- Ribs develop within the sheets
Support for the musculature provided by ________________
Vertebral column (backbone)
What are elements of vertebral column in vertebrates (deuterostomes) called?
Centra
- Notochord (stiff supporting rod) runs through the vertebral centra
- Hollow spinal cord passes through vertebral arches
What deuterostome shows a pineal “eye”
Archetypal vertebrate
What is a very ancient character in vertebrates?
Presence of lungs
What evolved from lungs?
Swim bladders
What was the structure that used to be on the top of vertebrates skulls and what is it now?
It was a third eye on the top of the skull called the pineal eye that actually had a lens on it to sense light…now it is a pineal gland (regulates sleep)
Why do the spinal cord of vertebrates enlarge?
To form a three part, hollow brain.
- Brain enclosed in a bony or cartilaginous cranium
- Sense organs access the environment through openings in the skull
Two evolutionary trends in vertebrates?
- Enlargement of forebrains
- Transfer of midbrain / hindbrain functions thereto
What comes first? Skull or crania?
Crania comes first and skull comes second
In deuterostome vertebrates where is anterior to the anus?
Muscle mass that is dorsal to and ancases visceral (internal) organs
In vertebrates what is posterior to the anus?
A post-anal tail that is comprised principally of muscles and support tissue
What do each part of a vertebrate brain do?
- Forebrain: Recieves and integrates olfactory, auditory, and visual input
- Midbrain: Coordinates responses to visual and auditory input
- Hindbrain: Exercises reflex control over tasks such as respiration and circulation
What structures are vertebrate segmentation restricted to?
- Trunk muscles
- Vertebrae
- Ribs
- Nerves and blood vessels
How is vertebrate segmentation different from annelid and ecdysozoan segmentation?
Annelid and ecdysozoan segmentation include duplicsation of visceral structures whereas vertebrate segmentation does not
How do vertebrate segments develop sequentially?
From structures called somites
How do somites develop?
Somites develop from embryonic mesoderm
- Somite development is induced by signals from other embryonic structures including the neural tube (becomes the dorsal nerve cord), the notochord and surrounding tiddues
What structures do somites give rise to?
Somites give rise to muscles, connective tissue and bone
T or F: Most vertebrates have paired appendages on either side of their body
true
What did vertebrate’s paired appendages first appear as?
First appeared as fins in jawed fish in the line leading to tetrapods. Fins later evolved into limbs
What did fins in vertebrate later evolve into?
Limbs
Why do all tetrapods have 5 fingers?
A long time ago 5 fingers was the way to go and now its just evolutionary baggage
In primitive vertebrates, water….
- Entered through the mouth
- Passed over the gills; food particles strained out
- Exited through gill slits on the animnal’s side near the head
In placoderms (primitive vertebrate) gill function transitioned from _____ to _______.
filter feeding to respiration
Characteristics of Placoderms
- Extinct
- Paraphyletic group
- First appear in late Silurian; abundant in Devonian
- Anterior gill arches modified to form jaws
- One known species with fish-life jaw bones
- Rest had parrot-like jaws with boney plates substituting for teeth
How does blood flow and respiration work in vertebrates?
- Deoxygenated blood pumped anteriorly by the heart and then over the gills through aortic arches
- Re-oxygenated blood flows posteriorly to the tissues
- The gills supported by cartilaginous / bony gill arches
What is an example of waste products in blood flow and respiration in vertebrates and what is the advantage of this in and out blood/water system?
CO2 and NH4+ are by products if the nitrogen metabolism which are then exchanged for oxygen. This is an example of a countercurrent exchange which maximizes oxygen
Why is the countercurrent exchange of by-products and oxygen good?
It maintains a high concentration gradient between water and blood
What is the equation for Fick’s Law of Diffusion?
.
Features and relationships regarding Ficks law of diffusion
- Solutes diffuse from regions of higher concentration to lower concentration
- Approximately, the rate of diffusion (flux)…
- Increases with concentration gradient (P2-P1), surface area (A)
- Decreases with membrane thickness
- Applies to heat conduction as well as to fluid flow
What do “Hot” fish do?
They keep swimming muscles warm by placing blood vessels leading to and away from the core in close proximity to produce a countercurrent exchange
How are wading bird’s anatomy advantageous for countercurrent exchange?
Wading birds have a similar arrangement in the legs to prevent loss of body heat to the water in which they stand
Do kidneys have countercurrent exchange?
Yes; they facilitate waste product concentration
Insects and countercurrent exchange
Some insects have a similar arrangement to keep heat generated by flight muscles in the thorax
- When ambient temperatures are high, honey bees also regurgitate fluids to evaporatively cool head and thorax
Many steps in vertebrate evolution recapitulated during development, for example…
- Gill arches become jaws
- Upper jaw fuses to braincase to become the tetrapod skull
- Reptilian jaw hinge becomes mammalian ear bones
How did mammals get the inner ear bones?
Opossums and marsupials have little bits of tissues at the back of the jaw and skull that then fall off and become the inner ear bones that all mammals hav
What is the modern version of “Ontogenetic Law”
Development recapitualtes embryonic states of ancestral forms (one thing changes course and turns into another)
Rube Goldberg character of evolutionary change Schaffer computer science edition:
When schaffer was young he had no graphic libraries so he had to write his own sub routines to light up a pixel. He then built a wrapper that was built in a more advanced system that gave the coordinates of the pixel that would light up. In all of the sub routines with the communication of info they never changed things at the lower level, they would only change things at the higher level that called to things at the lower level. So evolution just picks something small in the higher level to change the small basic things by calling them differently
- This is one of the basises of the three domain scheme
What is the Tunicate Larva Theory?
- Amphioxus-like chordates derive from the larvae of sessile urochordates such as living tunicates
- Larvae became sexually competent (paedogenesis) with the accompanying loss of the sessile adult phase
- Tunicate larva theory recently supported apparent presence notochord and gill slits in Vetulicolia
- Small worm-like animals previously blieved to legless arthropod
- Expanded pharynx at the front of the animal
- Segmented tail at the back
Bilateriam Ancestry Theory
- Urochordaye ancestors bilaterally symmetric
- Tunicate adult form an evolutionary “add-on”
Is the Bilaterian Ancestry Theory or the Tunicate Larva Theory correct for where vertebrate ancestors came from?
Unsure; In either case, an important theme of early vertebrate evolution was the progressive integration of viscera (digestive organs and related) and soma (trunk muscles)
Suppose that echinoderms were originally bilaterally symmetric. How would that change the synapomorphies in the cladogram on page 2?
If echinoderms were originally bilaterally symmetric, what factor(s) might have selected for the evolution of “radial,” i.e. pentameral symmetry in adults?
1st echinoderms (crinoids) sessile, i.e., attached to the substrate by a stalk. Radial symmetry facilitates for sampling all quarters of the environment. No need for bilateral symmetry – animals didn’t swim, crawl, etc.
How do tube feet work?
Hydrostatic pressure generated by the water vascular system causes the tube feet to extend – the protruding parts called “podia”. Most textbooks stop there. Some, Freeman included, refer to gripping and releasing the substrate; others, to suction. In fact, it now appears that both attachment and release are mediated by chemicals secreted by special cells in the tube feet. First a film is released; then a mesh that “bulks up” reminding me, at least to me, of “Gorilla Glue”. At this point, the foot is firmly attached to the substrate. Substrate release is mediated by re- lease of a third chemical. Chemical adhesion, it should be noted, is consistent with the observation that starfish can walk on porous substrates – screens for example – to which the tube feet couldn’t attach by suction.
How does a starfish (sea star) eat a clam?
a. Pries the valves apart – just a tiny bit – with tube feet. b. Everts part of its stomach. c. Slips the stomach between the valves. d. Digests the clam in situ.
Crossopterygian fishes crawled out of Devonian streams and ponds some 370 million years ago. Give two rea- sons why they might have done so.
- Access to abundant food supply, especially arthropods in the surrounding woodlands which may have been partially flooded.
- Escape from ponds / streams that dried up seasonally.
Redraw the scenario on the page 23 assuming a motile, bilaterian ancestor
Tetrapods and insects both obtain oxygen from the air. Compare gas exchange and transport in these two groups. Relate to insect size past and present. (Requires outside reading).
Look online
Information about the coelacenth
- Only living crossopterygian
- Not directly on the line leading to land animals but close
- Initially thought extinct until 1938
- Air bladder
- Back in Mesozoic these guys lived in fresh water then with tetrapod evolution they moved to deep water
- Last found in the Cretaceous
Four surviving groups of Vertebrates
- Agnatha - Jawless fish
- Chondrichthyes - sharks and rays (cartilaginous)
- Osteichthyes - bony fish
- Tetrapods - amphibians, reptiles, birds, mammals
What are agnatha?
A group of vertebrates that include jawless fish
What are chondrichthyes?
A group of surviving vertebrates that include sharks and rays (cartilaginous)
What are osteichthyes?
A group of vertebrates that include bony fish
What are tetrapods (what group are they in and give 4 examples)?
A group of vertebrates including amphibians, reptiles, birds, and mammals
What now extinct group of freshwater organisms did tetrapods evolve from?
Lobefin fishes
What is the only living lobefin?
Coelacanth
- Its a tetrapod
- It is secondarily marine
Review the timeline of vertebrates from the cambrian to the permian
The first vertebrates were _______ .
Jawless
What are ostracoderms?
A group of vertebrates that included the principal fossil representative of agnatha (jawless fish). Ostracoderms has external boney armor
What are two living forms of ostracoderms (vertebrates)?
They are cyclostomes which are hagfish and lamprey. They both lack bony skeletons
What special feeding structure do hagfish (vertebrates) have?
Special feeding structure for bottom scavenging
What special feeding structure do lamprey (vertebrates) have?
Blood sucking structure
What cyclostome (living ostracoderm vertebrate) has sessil “ammocete” larvae that resemble Amphioxus?
Lamprey
What structure allows lampreys (cyclostome vertebates) to burrow into the flesh of creatures?
Tongue rasp
What did jaws evolve from in vertebrates?
The third pair of gill arches (bony gill supports)
What did the fourth gill arch in vertebrates become and what was it called?
It became the hyomandibular which binds the jaws to the cranium
What did the third gill slit (not thirs pair of gill arches) reduce to?
It reduced to a small opening called the “spiracle”
_______ fused to the ______ in vertebrate evolution to form the jaw.
Mandible fused to the cranium
What differentiate from hypomandibular bone in the vertebrates?
Stapes (middle ear) and hyoid (supports tongue)
Overview of how vertebrates got jaws
- 4th gill arch became hyomandibular (binds jaw to cranium)
- Third gill slit reduced to small opening, called the “spiracle”
- Mandible fused to the cranium
- Stapes (middle ear) and hyoid (supports tongue) differentiated from hyomandibular bone
What class of vertebrates did the first jaw appear in?
Placoderms; they are now extinct
T or F: All extinct vertebrates had paired fins
False; some had paired fins and they included:
- Giant arthrodire with parrot-like beaks;
- “Spiny sharks” close to, but off
Why did antiarchs (placoderm chordata) have jointed flippers?
Possibly used for walking on and or digging into the substrate (burrows)
Why are spiny sharks disqualified from being direct ancestors of modern fish?
They have tooth-like structures in their mouths that were actually bony plates unrelated to teeth
What two classes are modern “fish” divided into?
Chondrichthyes (cartilaginous fishes) - sharks and rays
Osteichthyes (bony fishes) - everything else
What is chondrichthyes and osteichthyes phylum?
Chordata
What is the basic split between bony fish?
Actinopterygians (ray-fin fishes) and sarcopterygians (lobe-fin fishes)
What do Sarcopterygians (chordata) include?
- Crossopterygians, which in turn include
- Tetrapod ancestors
- Coelacanths - marine offshoot of basal stock
- Lungfish
Characteristics of actinopterygians (chordata)
- Descendants of marine placeoderms that invaded fresh water
- Re-invaded marine environments during the Mesozoic
- May have contributed to ichthyosaur extinction
T or F: Sarcopterygian fishes are devonian species close to the ancestry of tetrapods
True
What connection has been lost and what is now a swim bladder contains specialized tissue that secretes / re-absorbs gas
Polypterus where a bilobed, ventral lung connects to the pharynx thereby allowing for respiratory function
What do recent studies of living animals indicate about the location of air breathing?
Breathing occurs in dorsally situated spiracles as well as the mouth (air gulping)
Key fish-amphibian intermediate where dorsally situated spiracles are found?
Tiktaalik
What make the Tiktaalik a fish-amphibian intermediate?
- Like a land animal
- Neck
- Wrists
- Flat head
- Expanded ribs
- Like a lobe-finned fish
- Fins
- Scales
- Primitive jaws
Characteristics of Crossopterygians
- Retained the primitive ventral lung, which became the principal respiratory organ in the adult
- Paired fins evolved into legs in line leading to Amphibia
- Involved
- Loss of dominance of central axis
- Differentiation of wrist and finger bones
- Not observed in coelacanths and lungfish
- Involved
Look at the Crossopterygian fin anatomy
What does the amniotic egg allow for animals to do?
Allows for embryo to develop on land
What does the amniotic egg’s porous shell allow for?
Allows for gas exchange with the environment
Name 4 Extra embryonic membranes
- Chorion: Permits gas exchange; retains water
- Amnion surrounding embryo => an internal “pond”
- Yolk sac encases food supplu
- Allantois stores metabolic waste
How do reptile/bird and mammal ectraembyronic membranes differ?
Reptile/Bird have larger allntois and yolk sac whereas mammals have larger chorion and amnion
T or F: Internal fertilization is a key feature that helped complete the water to land transition
True
THREE KEY FEATURES THAT HELPED COMPLETE THE TRANSITION FROM WATER TO LAND
- Amniotic egg
- Internal fertilization
- Water conservation
Features of water conservation in animals
- Fluid retention by a water impermeable tough membrane
- Urine concentration by the kidneys (only mammals and bird profuce urine more concentrated than blood)
- Water reabsorption by the colon (and cloaca in birds and reptiles)
- Converstion of ammonia to less toxic compounds: uric acid or urea
Consequences of conversion of ammonia to less toxic compounds such as uric acid or urea
- Permits concentrated urin / avoids dehydration
- Likewise avoids ammonia toxicity
- Require energy expenditure
When did more active animals begin to appear and what were they?
In the permian and Triassic, Both archosaurs and synapsids evolved more active life styles
List 8 signs of more active life styles
- Posture
- Energy production
- Respiration
- Food processing/ chewing
- Secondary bony palate in Synapsids
- Four chambered hearts
- Birds/mammals are endothermic
- High body temperature requires generation and retention
Signs that posture was a signal that animals were getting more active
- Tucked the legs under the body
- Synapsids quadrupedal; archosaurs, bipedal
- Side to side wriggling replaced by back and forth motion of legs
- Increased speeds
Erect posture + broadening of anterior rib cage =
= enhanced oxidative metabolism
Deeper chest = larger lungs = more air = better oxygenation of blood = more O2 =
= greater endurance (longer time before muscles switch from aerobic respiration to glycolysis
Explain how respiration changes indicated animals were becoming more active
- Breathing in mammals is tidal
- Inspiratory volume enhanced by diaphragm; i.e. lungs expand
- Avian dinosaurs (birds) use a flow-through system of air sacs and non-expansive lungs
- Some dinosaurs had air sacs
Explain how food processing and chewing changes indicated animals were becoming more active
- Fenestration (holes) of skull independently acquired in both groups allows for larger/bulging jaw muscles
- Mammals: differentiated teeth - especially molariform teeth with cusps for grinding
- Archosaurs: Gizzards
Explanations as to why crocodiles for example (but not dinosaurs) have secondary bony palates
- Breathe while you chew
- Help resist the forces generated when the animals chews
Two important facts about the evolution of the four chambered heart
- Independently evolved in archosaurs and synapsids
- Complete separation of oxygenated and deoxygenated blood
Are birds and mammals endo or exothermic
Endothermic
How is high body temperature maintained in mammals?
Through the growth of hair
How is high body temperature maintained in dinosaurs and birds?
Feathers
Three different concepts confound by the terms warm- and cold-blooded
- Source of heat: ectothermy (external) vs endothermy (internal)
- Metabolic rate (MR): bradymetabolic (low rate) vs. tachymetabolic (high rate)
- Temperature regulation: poikilothermy (unregilated) vs homeothermy (regulated)
Are hot or cold blooded animals typically ectothermic bradymetabolic poikilotherm?
Typically cold-blooded animals
- Heat from the enviornment
- Low MR/ food intake
- Internal temperature fluctuates with external
- Becomes torpid when its cold
- Behavioral temperature regulation in some (basking)
Are warm or cold blooded animals typically endothermic tachymetabolic homeotherm?
Warm-blooded
- Generates heat internally
- High MR/ food intake
- Regulates internal temperatures
- Usually but not always correlated - ex. hummingbirds go torpid on cold nights and can freeze to death
Two example reactions to warm-blooded animals in extreme temperatures
- Rat in the box experiment: Rat shakes in freezing temperatures, pants in warm temperatures, and dies if it is in too hot of a temperature
- Hands get red in snow because arteries open up to cool down
Three living groups of mammals
- Monotreme (prototheria) - lay eggs
- Marsupials (metatherians) - live birth, pouch
- Placental (eutherians) - extended gestation, no pouch
When did mammals originate?
Originate in Triassic
- Coevolve with first dinosaurs
- First 2/3 of mammalian evolution before chicxulub wiped out non-avian dinosaurs
Basic facts about primates
- Descended from free-living cretaceous insectivores
- Grasping hand and feet, opposable big toe, nails
- Eyes directed forwatf; binocular vision
- Two main groups: Prosimians and anthropoids
What are the two main groups of primates?
Prosimians and anthropoids
Characteristics of prosimians (one of the two main groups of primates)
- Tree shrews, lemurs, etc.
- Nocturnal
- Most in Madagascar
Characteristics and examples of Anthropoids (One of the two main groups of primates)
- Tarsiers
- New world monkeys
- Arboreal
- Many have prehensile tails
- Rafted over from Africa
- Old world monkeys - arboreal and terrestrial
- Apes
- Arms elongate
- Brachiators and knuckle walkers
- Hominins
What is an Aye aye?
It is a lemur that essentially wanted to be something else
How do Aye ayes find food?
Aye ayes tap on the wood/bark to see if its hollow and it it is then it gnaws on the wood and sticks its finger in the hole and grabs out a grub
When did Hominins diverge from Great apes?
About 6 MYA
What are features of Australopithecines (early african hominins)?
- Bipedal (small brains but could walk on their hind legs)
- Robust, gracile species
Five trends in Hominid evolution
- Arms shorten
- Legs elongate
- Face and jaws foreshortening; tooth size reduce
- Body size, cranial capacity increase
- Increasing protein consumption => larger brains. Facilitated by
- Manufacture of weapons
- Adaptation for running including hair loss/sweat gland proliferation
What are all adaptations in hominins a cause of
Juvenilization
19th century hominid fossils variously interpreted as…
- Within the range of modern human variability (Huxley)
- Diseased humans - e.g. microcephalic idiots; representative of “lower” modern races
T or F: Our brain is the largest it has ever been for all hominins
False; Large neanderthal cranial capacity suggested that human brain had been larger in the past
What discovery marked the accepting of human ancestors are bipedal but small-brained?
The discovery of Australopithecus (early hominin)
What does early reconstructions of hominid evolution suggest and the progess from ape to man and what does it reflect?
Suggests linear progress (orthogenesis) and reflected
- Lack of fossils
- Presistent ideas of directed (or self-directed) evolution
- Evolution with a purpose to get humans
Contemporary paleoanthropology emphasizes….
“Bushiness” of human evolutionary tree meaning it was not at all linear
Difference between orthogenesis and bushiness of human progression
- Orthogenesis says that the progression from ape to human was linear
- Bushiness says that the progression from ape to human was bushy
What is referenced when the idea that we started out as worms?
Darwin’s last book, The Formation of Vegetable Mould, through the Actions of Worms
As Darwin predicted, Africa turned out to be the birth place of man True of False
True
- There were multiple migrations to other continents thereafter
What species made the first tools? and where were they found?
Homo habilis in Olduvai Gorge, Africa
Facts about Homo erectus
- First known use of fire
- Coexisted with and may have exterminated African Australopithacines
- Replaced by Homo sapiens about 200,000 years BP
What did H. sapiens replace?
- H. erectus about 200,000 y BP
- H. s. neanderthalis 30,000-50,000 y BP
Where, when, and what is key about the Agricultural revolution?
- Where: Fertile crescent
- When: 10,000 y BP
- KEY: Self-domestication
Possible cause for H. sapiens replacing H. erectus and H. s. neanderthalis?
Recent DNA analysis shows that there was interbreeding
T or F: H. erectus may have inhabited Eurasia first before inhabiting Africa
True
Tiktaalik bridges the gap between fish and tetrapods by virtue of possessing which of the following?
a. Humerus.
b. Radius.
c. Ulna.
d. Wrist bones.
D. wrist bones
Morphologically, lungfish appear to be further from the ancestry of tetrapods than crossopterygians because they lack…
differentiated fin bones homologous to the radius and ulna.
Regarding the evolution of the mammalian jaw and middle ear: a. The articular bone in reptiles is to the quadrate as the ________ in mammals is to the ________. b.The reptile articular bone became the _______ in mammals; the quadrate, the ____.
dentry to squamosal; malleus to incus
On several occasions this semester, it has been observed that “reptiles” as traditionally defined (snakes, lizards, turtles, croc- odiles) is a _________ group. Yet in Figure 34-12 (page 654) of your text (4th edition), Reptilia is represented as a clade with Egg number vs. size in silver salm- on. From Shapovalova and Taft (1954). “scales with hard keratin” given as the synapomorphy. What gives?
Paraphyletic
Synapsid lungs are expansive; avian lungs, not. Explain.
Respiration in synapsids is tidal with expansive lungs allowing for greater inspiratory volume. In contrast, avian respiration is flow-through. No need for lungs to expand as air is continuously pumped through them.
What was the Piltdown forgery? Who was responsible? (Requires outside reading. Be sure to cite sources)
Piltdown man was a hoax in which an orangutan jaw bone and parts of a modern human skull, all stained to make them appear old, were represented as the remains of a pre-human hominid. The remains were “discovered” by Charles Dawson, an English- man, in 1912, and, despite some objections, were generally considered genuine for forty years. As such, they were con-Piltdown reconstruction, From Oakley and Weiner (1953).
sistent with the late 19th / early 20th century view that large brains were an early hominid innovation. Accumulating evidence for small-brained, bipedal australopithecines set the stage for Dawson’s find’s being discredited in 1953. The identity of the perpetrator(s) remains uncertain, although Dawson is generally considered a prime suspect
The Triassic witnessed the evolution of dinosaurs and mam- mals, the latter having descended from much larger, “mammal- like” reptiles that were the dominant tetrapods during the Permian. In short, species belonging to the lineage leading to mammals got smaller while archosaurs got larger. Discuss in terms of changing levels of atmospheric oxygen during the late Permian and early to mid-Triassic. (Requires outside reading. Be sure to cite sources)
During the late Permian and early Triassic, atmospheric oxygen levels are believed to have plummeted. One can speculate that selection would have favored small body size in tetrapods with tidal respiration (line leading to mmmals), but not in species with flow- through respiration. If archosaurs had already evolved a bird-like system of air sacs, diverging body size in the two lineages could thereby be ex- plained.
Modern hunter gatherers hunt large mammals by pursuing (running / jogging / walking) their much faster prey until the latter collapse. Discuss in terms of temperature regulation by ungulates and man.
“Persistence hunting” works because humans lack body hair. This allows them to thermoregulate more efficiently than large ungulates that pant and must slow down in order to do so. The difference allows human hunters to pursue their prey, sometimes for days, until the latter collapse, at which point they are easily dispatched.
What do colonial corals secrete?
Calcerous shells
What is a coral ring around a body of water called?
A lagoon
What was Darwins uniformitarian solution to how coral reefs form?
A balance bwteen reef expansion and island subsidence
What is a statocyst in comb jellies?
A gravity sensitive structure that gives them a sense of up and down
What is the phylum of Rotifers (wheel animals)
Rotifera
How do the tube feet of octipi and starfish stick to substrate?
They secrete adhesive
What is the purpose of a countercurrent exchange between oxygen and blood?
It maintains the most favorable gradients
Three stages of Kidney development in humans
- Pronephros: Initially there but disappears after the fourth week -> vestigial structure
- Mesonephros: Principal in weeks 4-8 but then degenerates. Becomes associated with male reproductive organs
- Metanephros: occurs after 5 weeks of development and is the main structure
T or F: Echinoderms have tubed feet
False!!! They have adhesive forces
Difference between filter feeders and suspension feeders
Filter feeders: Actively generate current (for example with collar cells)
Suspension feeders: Grab particles
What are choanocytes?
Collar cells that create a current in sponges
Echinoderms symmetry in larvae vs adult
Larvae: Bilateral symmetry
Adult: Pentaradial symmetry
What type of feeders are coral
Suspension feeders
What is the stinging structure on cnydaria?
Nematocysts
T or F: Dolphins, snakes, and whales are tetrapods
True
Why are dolphins, snakes, and whales tetrapods?
They have the ability to grow legs and or their ancestors used to have four legs
- They also have vestigial pelvises
What is a main molecule in the ocean?
CaCO3
Difference between Tunicate-larvae theory and Bilaterian ancestry theory
Tunicate larvae theory: Derived trait is motile adult (think tunicate is flexible = motile)
Bilaterian ancestry theory: Derived trait is sessile adult
Tunicate larvae theory recently supported the apparent presence of ____ in Vetulicolia?
Notochords and gill slits
What are important themes of the early vertebrate evolution?
An important theme of early vertebrate evolution was the progressive integration of viscera (digestive organs and related) and soma (trunk muscles)
How do tube feet work?
By manipulating the water vascular system to facilitate movement and utilizing sticky adhesive to surfaces
What species of the genus Homo was the first to develop tools?
H. habilis
Water vascular systems are composed of …
Calcififed, hydraulic canals
What is the top of a sponge called?
An osculum
What type of cell is responsible for generating the current within a sea sponge?
Choanocytes aka collar cells
Corals produce a skeleton made of _____
Calcium carbonate
Charophyte algae use what for support?
CaCO3