MB Study Guide: Reptiles, Birds, Mammals

Subphylum: Vertebrata (review)

• A backbone or vertebral column.

• An endoskeleton made of either cartilage or bone.

• A closed circulatory system with a heart.

• A distinct head with a brain protected by a skull

Class Chondrichthyes: cartilaginous fishes (sharks, rays, skates)

Class Osteichthyes: bony fishes (tuna, salmon, clownfish)

Vertebrate Class

1. Reptilia

2. Aves

3. Mammalia

Class Reptilia Characteristics (species, scales, body form)

• around 7000 species, but only 1% are marine

• Body covered with dry scales

• leathery eggshells- adapted to terrestrial nesting

• ectothermic (cold blooded): body temp depends on environment

• salt glands: help marine species execrete excess salt

Class Reptilia Marine Representatives:

1. Sea Turtles: 7-8 species

2. sea snakes: 60 species

3. marine iguana

4. marine crocodile

Sea Turtles (7-8 species)

• Found in warm tropical and subtropical seas.

• Females return to land to lay eggs. 

• Eat jellyfish, seagrass, and invertebrates depending on species.

• Threatened by pollution, fishing nets, and coastal development.

Sea Snakes (60 species)

• Found mainly in the Indo-Pacific.

• Extremely venomous.

• Flattened tails aid in swimming.

• Rely on cutaneous respiration (some gas exchange through skin)

Marine Iguana (galapagos islands)

• Only sea-going lizard.

• Feeds on marine algae.

• Regulates body heat by basking on rocks.

Marine Crocodile (Saltwater crocodile, Crocodylus porosus)

• Largest living reptile.

• Found in brackish and coastal waters of Indo-Pacific region.

• Ambush predator—feeds on fish, birds, and mammals.

Vertebrate Class: Aves

• birds

• around 7000 species, but only 1% are marine

Vertebrate Class: Aves characteristics (skeleton, shells, body temp)

• body covered with waterproof feathers (coated with oil)

• hard-shelled eggs: laid and incubated on land (sea birds nest on land)

• Endothermic (warm blooded): maintain constant body temp (body temp regulated)

• Hollow bones: make them lighter for flying

• High metabolism: needed for sustained flight & cold environments

Vertebrate Class: Aves Diet

consume large amts of high quality protein:

• primarily fish

• some feed on plankton

Aves (marine birds) Representative Groups

• penguins

• tubenoses (albatrosses, petrels, & shearwaters)

• pelicans

• gulls

• terns

• many other groups that inhabit the edge of the sea: greets, ducks, herons, sandpipers, & plovers

Vertebrate Class: Mammalia

• about 4600 species, but fewer than 2.5% are marine

Vertebrate Class: Mammalia Characteristics

• body covered with hair (reduced in some marine forms)

• Viviparous- give birth to live young

• Placenta: nourishes developing embryo and born live

• Mammary glands: produce milk to nourish/feed young

• Endothermic: maintain constant internal temp; body temp regulated

• high intelligence

Mammalia Marine Species Include:

1. Order Cetacea

2. Order Sirenia

3. Order Carnivora

4. Order: Pinnipedia

Order Cetacea

Includes whales, dolphins, and porpoises.

● Fully aquatic.

● Streamlined bodies, horizontal tail flukes.

● Breathe air via blowhole(s

Order Sirenia

Includes manatees and dugongs.

● Herbivorous (feed on seagrasses).

● Slow-moving, live in warm coastal waters and rivers.

● Threatened by boat collisions and habitat loss.

Order Carnivora

Includes sea otters and polar bears.

● Sea otter: uses tools (rocks) to crack shells; maintains kelp forest balance.

● Polar bear: marine apex predator feeding on seals

Order Pinnipedia

Includes seals, sea lions, and walruses.

● Semi-aquatic.

● Thick blubber for insulation.

● Seals: lack external ears, swim with hind flippers.

● Sea lions: have external ears, use front flippers to “walk.”

● Walrus: long tusks used for defense and hauling out on ice.