L17 - Marine mammals Flashcards
(44 cards)
What are marine mammals?
Heterotrophic - consumers, homeothermic - maintain constant body temp independent of ambient temperature. Endotherm (as all mammals) - warm-blooded animal creating heat internally, air breathing - have lungs, exchange gasses directly with the atmosphere. Viviparous - give birth to live young, have hair or fur. Nurse young with milk (have mammary glands), live partly or fully in marine/aquatic environment. K-selected species (populations fluctuate at or near carrying capacity (K)), stable pops, low offspring, long gestation, slow maturation, extended parental care and long life spans
Where in the world?
From extremely large to very small ranges
What are mammals and sharks? Endo or ectotherms?
Endotherms - mammals (115 spp)
Ectotherms - sharks (242 spp)
What is the taxonomic groups of Cetaceans?
Order Artiodactyla, even toed ungulates) the whales, porpoises, and dolphins
What is the taxonomic groups of Pinnipeds?
Order Carnivora, seals, sea lions, walruses. They use flippers to move both on land and in the water.
What is the taxonomic groups of Sirenians?
Order - Afrotheria, Paenungulata, manatees and dugongs
What is the taxonomic groups of marine fissipeds?
Order carnivora, sea otters and polar bears.
What are the Cetaceans?
Whales, dolphins, porpoises. Baleen whales (mysticetes) and toothed whales (odontocetes). Planktivores, piscivores, and carnivores. They spend their lives in water and have many adaptations to their entirely aquatic lifestyle. There are over 90 different species of cetacean from the smallest Hector’s dolphin and the Vaquita (1.2m) to the blue whale (nearly 30m and 199 tonnes).
What are the Cetaceans? pt2
Approx 28 species recorded in the Uk, and wales has four common regularly sighted cetaceans and another four regularly see but not as common. Unusual species strandings also happen from time to time. Planktivores, piscivores and carnivores with variety of feeding tactics and techniques: lung feeding, bubble netting, shore chasing, jumping in and out of trawler nets, tail slapping, and giant stunning clicks of the spermwhale.
What are Mysticeti?
13 spp, filterfeeders: baleen traps krill or bait fish, water is forced back out of the mouth. Ex. Blue, fin, grey, humpback, minke whales
How is there iron nutrient cycling?
Whale poop to phytoplankton conveyor belt in the water column for nutrient cycling (iron). Recovering baleen whale populations may also increase phytoplankton may also increase CO2 sequestration in oceans.
What are Odontoceti?
> 70spp. Simple, peg-like teeth, considerable variation between species; adapted for grasping and tearing, not chewing. Diet: fishes, squids, bottom invertebrates. Include dolphins, porpoises, belugas, narwhals, sperm, orcas, river dolphins, and beaked whales
What are Pinnipeds?
36 extant species, 50+ extinct. Pinnipedia means ‘fin-footed’. Spend the majority of their lives swimming and feeding in water. Come onto land or ice flows to give birth to young, rest, and moult. Include - true seals (Phocidae), eared eals: sea lions and fur seals (Otariidae) and walrus (Odobenidae)
What is the features of sea lions and fur seals?
external ear, long neck, external testicles in males, posterior flippers can be moved forward, anterior flippers used in swimming. Anterior flippers rotate backward to support weight and keep head erect; undersurface and edge not covered with hair or nails to reduce water resistance in swimming
What is the features of seals?
Short neck, no external ear, anterior flippers covered with hair, five toes with sharp nails; they cannot be rotated backward. No external tescticles in males, use posterior flippers in swimming; they cannot be moved forward.
What are sirenians?
Manatees (trichechidae) and the dugong (dugongidae). Spend their whole lives in water. The only entirely herbivorous group of marine mammals. All four species endangered or threatened, particularly dugong.
What are Sea otters (Enhydra lutris)?
Fully aquatic. Adult sea otters may eat as much as 9kg of food each day: sea urchins, crabs, abalone, clams, mussels, octopuses, and fish. Also the marine otter (Lontra felina) a small species found in south america, which lives in coastal areas is considred by some to be a type of sea otter but they spend considerably more time on land.
What are Polar bear (Ursus maritimus)?
Polar bear - the largest land carnivore, specialised adaptations to Arctic and marine environment. Adult polar bears need an average of 2kg of fat per day to maintain their weight; diet includes mostly ringed and bearded seals but also other seal species, walrus, narwhal, beluga whale, whale carcasses, fish, birds, eggs, berries, and kelp
What are the ecological functions?
Marine mammals represent a variety of ecological roles, including herbivores (manatees), filter feeders (baleen whales), piscivores (dolphins and porpoises) and top predators (orca and polar bear) who predate on other marine mammals. Transfer of nutrients (downward via death, upward via defaecation in euphotic zone). Community structure - sea otters predate on urchins - kelp forest develop; dugong grazing increases seagrass productivity (germination rates improved if eaten by dugongs). Benthic habitat modifiers - sediment turnover created by a walrus feeding promotes early colonisers (amphipods).
What are trophic niches & ecosystem changes?
Marine mammals span the full range of ecosystem macrofauna, from obligate planktivores to apex carnivores. They include sympagic (solid ice), pelagic, benthic and deep-sea feeding species, representing low/mid and high trophic levels. MacKenzie et al, 2022, empirically defined the trophic function, nutrient sources and degree of specialisation of marine mammals feeding in the arctic waters around svalbard. Strong niche partitioning and little between species functional redundancy. Each species fills a distinct niche. So loss of any of these species can lead to ecosystem-scale effects and reciprocally, changes in these vulnerable ecosystems could result in reduction or loss of these species in the european arctic.
What is marine mammal evolution?
Back to the sea after 300 million years. Each taxonomic marine mammal group evolved from a different group of land mammals, whose ancestors separately ventured back into the ocean environment. Despite these different origins, many marine mammals evolved similar features - streamlined bodies, paddle-like limbs and tails. Through convergent evolution.
What is marine mammal convergent evolution?
The independent development of similar traits or features (as of body structure or behaviour) in unrelated or distant related species or lineages that typically occupy similar environments or ecological niches. The fossil record demonstrates that mammals re-entered the marine realm on at least seven separate occasions. Five of these clades are still extant.
What are the challenges of living in the aquatic enviro?
Breathing, regulating body t, relative weightlessness, movement, diving, communication, sound underwater, low-light enviro, sleeping, mating/nursing.
What are respiratory adaptations: breathing?
Adaptations to skeletal structure and locomotion. Streamlining, legs into paddles or fins for steerage, loss of hindlegs (cetaceans and sirenians), skin and blubber reducing drag, loss of external appendices (ears, genitalia). Large powerful tail fluke for efficient propulsion. Paired flipper movement in pinnipeds (and sea otter). Dorsoventral undulation in cetaceans and sirenians. Wave riding and porpoising reduces cost of transport. Dorsal fin for rotational stability. No need for pelvic bones to carry body weight-vestigal pelvis bones remain.
