Marine Biology: Marine Reptiles, Birds & Mammals

Vocabulary flashcards covering the phylogeny, adaptations, diversity, and specific physical characteristics of marine reptiles, seabirds, and mammals.

Convergent evolution

The process by which organisms from land and swamps adapted to the ocean, resulting in traits like swimming appendages and streamlining to overcome water's viscosity, which is $50\%$ more than air.

Endotherm

An animal that maintains an internal body temperature; mammals and birds are examples, though they experience a heat loss $40\times$ larger in water compared to air.

Ectotherm

An animal whose internal body temperature is determined by the environment; reptiles are ectotherms, which explains their absence from polar regions.

Salinity (Ocean)

The concentration of salt in the ocean, measured as $34\,ppt$ ($1000\,mOsm/l$), compared to the $300\,mOsm/l$ found in the blood of land vertebrates.

Marine iguana

A clumsy lizard species found in the Galapagos that grows up to $1\,m$ long, dives to $10\,m$, and feeds on seaweed.

Saltwater crocodile

A marine reptile with saltwater glands that can reach $6\,m$ and $1000\,kg$; it is an apex predator responsible for approximately $15$ human fatalities per year.

Sea snakes

A group of $70$ species of venomous carnivores related to the cobra, typically $1\text{--}1.3\,m$ long, that are hunted for their skin and meat.

Leatherback sea turtle

A sea turtle weighing $900\,kg$ with a 'shell' composed of small bones buried in the skin, capable of diving to depths of $640\,m$.

Countershading

A form of camouflage used by seabirds and other marine animals to blend in with the environment from above and below.

Oil gland

A specific bird gland used for waterproofing feathers.

Penguins

A group of $18$ flightless bird species found only in the Southern hemisphere that have adapted wings into flippers for swimming.

Divergent evolution (Seabirds)

The development of different beak morphologies among seabirds (e.g., Petrel vs. Tern) to allow for resource partitioning and niche diversification.

Sea otters

The largest mustelids ($30\,kg$) and a keystone species that consume $25\%$ of their body weight per day and are known for using tools.

Polar bear

A subspecies of the brown bear found in the Northern hemisphere that weighs roughly $700\,kg$ and primarily feeds on seals found on ice.

Sirenia

An order of marine mammals including Manatees and Dugongs; they are slow-moving herbivores related to elephants that weigh up to $500\,kg$.

Pinnipedia

A group of marine mammals comprising seals, sea-lions, and walruses, characterized by blubber, large brains, and being viviparous.

Cetacea

The order of whales and dolphins that evolved approximately $50$ million years ago from artiodactyl ungulates, who are relatives of hippos.

Baleen whales

Large, slow filter feeders with two blowholes and baleen plates made of keratin; they include the family Balaenopteridae (Rorquals).

Toothed whales

Fast-moving predators with a single blowhole and teeth, including dolphins and species like the Sperm whale.

Cuvier’s beaked whale

A species of toothed whale recorded diving to a depth of $2992\,m$.