Nekton

• Strong swimmers in the pelagic realm

Cephalopod Mollusks

• Pelagic = squid, cuttlefish, chambered nautilus

• (benthic = octopus)

• Have tentacles and are active predators

• Highly evolved nervous system

• Largest of the invertebrates (59 ft squid)

cuttlefishchambered nautilus

Squid

Giant Squid Captured, Filmed for First Time : Dec 22, 2006- Japan

Vertebrates:Cartilaginous Fish –

• Skeletons made of cartilage• skates, rays

– more benthic

– Dorsoventrally flattened

• sharks – More pelagic

– Torpedo shaped and streamlined

Fig. 13-13, p. 269

Fig. 13-14, p. 269

Cartilaginous Fish

• skeletons made of tough elastic cartilage

• negatively buoyant– Use fins for lift– Store oil in liver

• Gill slits are visible

• some of the active sharks must swim to breathe

Vertebrates: Bony Fish• Skeletons made of bone

• most numerous and successful of all vertebrates

Bony Fish

• swim bladders

Bony Fish

• operculum

Vertebrates: Marine Reptiles • Sea turtles, sea snakes, marine iguanas,

marine crocodiles

Marine Reptiles

• ectothermic

• covered with scales

• breathe air with lungs,

• have specialized salt glands to excrete excess salt taken in from seawater

Vertebrates: Marine Mammals• Class Mammalia

– mammary glands; hair – endothermic

Marine Mammals• Cetaceans

– porpoises, dolphins and whales– toothed whales & baleen whales

•Figure 14.25

Marine Mammals• Carnivora

– seals, sea lions, walruses, sea otters and polar bears

•Figure 14.18

Seals vs. Sea LionsSea Lions•external ear flaps•Large front flippers to propel themselves•Long neck

Seals•Pin hole for ear•Small front flippers with claws•Propel themselves with rear flippers•Less mobile on land

Marine Mammals

• Sirenia– manatees &

dugongs– only

herbivorous marine mammal

Marine Mammals

• streamlined bodies

• breathe air using lungs

• modified respiratory (get 90% of O2 out of the air) & circulatory system (more red blood cells, more hemoglobin and myoglobin) for prolonged dives

• osmotic adaptations