Lesson 21: Marine Mammals

Common characteristics Marine mammals share the following characteristics: Give birth to live young Nurse their young Endothermic – “warm blooded” Have hair

Marine Mammals Groups: Cetaceans (whales, dolphins, porpoises) Pinnipeds (seals, sea lions, walruses) Sirenians (manatees, dugongs) Polar Bears Sea Otters

What’s the difference between a dolphin and a porpoise? http://vimeo.com/75615317

The main difference between dolphins and porpoises is their teeth The main difference between dolphins and porpoises is their teeth! Dolphins have cone-shaped teeth, while porpoises have flattened, spade-shaped teeth.

While not a perfect rule, porpoises generally have a triangular dorsal fin while dolphins have a more curved dorsal fin.

Cetaceans Sleek, bullet shaped bodies Strong tail for propulsion Long “mouth” area called a rostrum Move their tails, or flukes up and down

Cetaceans Must breathe voluntarily (unlike humans) Breathe through special hole on top of their heads called a blowhole Deep divers remain near surface for several minutes to “catch their breath” Cloud-like blow is a mixture of CO2 and unused O2, liquid water spray, and mucus

Cetaceans Unlike most mammals, cetaceans do not have much hair Instead, layers of fat under skin called blubber Keeps animals warm and regulate body temperature

Two Major Groups 1) Suborder Odontoceti (Toothed whales) Dolphins Porpoises Beluga Whale Killer Whale Sperm Whale

Toothed Whale Characteristics Eat fish or squid Use teeth to rip apart prey Use sound to echolocate, navigate, communicate

Two Major Groups 2) Suborder Mysticeti (Baleen whales) Blue whales Humpback whales Gray whales Fin whales

Baleen Whales Baleen allows them to strain their food from the water Diet includes small prey such as krill, small fish and squid

NOAA describes 11 species of baleen whales, and 67 species of toothed whales.

Behavior of Cetaceans Vary widely between species Spinner dolphins swim in large pods Blue whales typically alone or in pairs Harbor porpoises prefer shallow waters Sperm whales prefer deep dives to chase squid Communicate using clicks, whistles, and groans

Why we Should Care About Whale Poo….. TED talk

Pinnipeds All pinnipeds are protected under the Marine Mammal Protection Act (MMPA); some may be designated as "depleted" under the MMPA. Endangered and threatened pinnipeds are further protected under the Endangered Species Act (ESA).

Pinnipeds Unique because they give birth and nurse on land Wide range of environments Leopard seal in icy Antarctic Ribbon Seals in Arctic Harbor Seal along temperate shorelines Hawaiian Monk Seals near Coral Reef

3 main groups Otaridae (Eared seals) Includes seals with fur and sea lions Have an earflap on outside of their bodies Use longer flippers to walk on land by twisting back limbs forward Ex: California Sea Lions, Steller Sea Lions, Northern Fur Seals

California Sea Lion pup

2) Phocidae (True Seals) Move on land by wriggling on their bellies vertical undulating motion called "galluphing” Ex: Hawaiian Monk Seals, Harbor Seals, and Ringed Seals Hawaiian Monk Seal Harbor Seals

Ringed Seal

3) Odobenidae (Walruses) Distinguished by long tusks Use tusks to dig up shellfish from seafloor

What’s the difference between seals and sea lions? Sea lions (left) are brown, bark loudly, "walk" on land using their large flippers and have visible ear flaps. Seals have small flippers, wriggle on their bellies on land, and lack visible ear flaps.

3) Odobenidae (Walruses) Also to break through ice and haul themselves onto ice Unlike other pinnipeds, have very little hair Very thick skin Coarse, sensitive bristles around mouths replaced yearly

Pinnipeds Many relax or “haul out” on land in large groups called colonies Occurs when mothers give birth Occurs when animals lose their fur, or molt Some species like Northern Elephant Seal lose their entire top layer of skin and hair

Pinnipeds Haul out areas are not always peaceful Baby Elephant Seal Haul out areas are not always peaceful Engage in violent fights over mates Northern Elephant Seal males establish dominance through intense fighting Wins them the right to mate with females Walruses behave similarly