Day 22 Mammals
Mammals (Class Mammalia)
Mammalian Characteristics
-Mammals are endothermic
-Most are viviparous (Give live birth)
-Have fur for warmth
-Females have mammary glands and feed their young milk
-Mammals have the largest brain to body weight ratio.
-Their large brains have been one of the contributing factors to their success
-Mammals are successful in all ecosystems on the planet
-All mammals evolved on land. Even the ancestors of whales lived and walked on land.
Ambulocetus
-Ancestor of whales and dolphins
Sea mammals also have other adaptations for living in the ocean with lungs
-Marine mammals have myoglobin. Land mammals use hemoglobin to transport oxygen through their body
-Marine mammals like dolphins use myoglobin because it can not only transport oxygen but it can store it
-Marine mammals like the sperm whale can hold their breath for hours
-Another marine mammal adaptation is while diving their heart only sends blood to vital organs and selectively ignores others
Order Pinnipedia (Pinnipeds)
Seals, Sea Lions, and The Walrus
-Pinnipeds have a paddle like flipper and need to rest on land
-The Pinnipeds evolved from an early ancestor of the Order Carnivora (Cats, dogs, and bears)
-Pinnepeds used to be in the order Carnivoria until they were given their own order.
Seals (Common Name)
-Seals have the largest amount of species for the pinnipeds
-Seals have no external ears
-The males have no external testicles
-Rear flippers cannot move forward
-Front flippers have claws and covered in fur
Watch this SciSHow video on Elephant Seals. Create a box or separate section in your sketchbook and title it "Elephant Seals". Take notes, write down anything you might find interesting and include a picture.
Watch and enjoy this short video of a Jonathan Bird swimming with a leopard seal
This is an optional video about the endangered Hawaiian Monk Seal
Sea Lions (Common Name)
-Have external ears
-Have external testicles
-Can rotate their rear flippers to face forward to support their weight while walking
-Have no claws or fur on their flippers
Walrus (Common Name)
-Have huge tusks in the front (Male and Female)
-Was thought to help with eating but no evidence for this
-Mostly used for fighting and anchoring to ice
Order Carnivora
-Sea otters and Polar Bears
Sea Otters (Common Name)
-Otters lack blubber so they have very thick fur to keep themselves warm
-Fur trappers capture them for their fur
-The sea otter is the smallest marine mammal
Polar Bear (Common Name)
-Polar Bears are semiaquatic, they have webbed paws and are great swimmers
-They spend most of their time on drifting ice
-They hunt and eat seals
Order Sirenia
-The Manatee
-Called the sea cow
-Believed to be related to elephants
-Named after the Sirens, they were thought to be mermaids
-Are herbivores. They mostly eat see grass
Order Cetaccea
-Whales, Dolphins, and Porpoises
-Convergent evolution
-Cetacceans look like fish but did not evolve from them
-The cetacceans were land mammals. That is why they have lungs
-The cetacceans have four limbs as embryos
-Cetacceans rear flipper is horizontal and fish have vertical rear flippers
-Unlike most mammals the cetaccean nostril is not in the front of the face but on their back
-Blow Hole
-The cetacceans are mammals that never need to come on land
-The blow hole helps them to breath with very little breach of the surface
Watch this PBS video on Whale Evolution. Create a box or separate section in your sketchbook and title it "Whale Evolution". Take notes, write down anything you might find interesting and include a picture.
This is an optional but very interesting video on whale evolution
Baleen Whales (Toothless Whales)
-Instead of teeth baleeen whales have fibrous plates called baleen
-Baleen is made of keratin just like hair or nails
-Water is taken into the mouth and then pushed back out through the baleen
-The baleen filters the water out but leaves the organic matter inside
-The whale then swallows the organic matter
-Most baleen whales eat krill
-Baleen whales are the largest animals in the world
-A blue whale can be between 80 and 100ft
-One of the largest animals to ever live
Enjoy this short video where Jonathan Bird swims with a humpback whale and its baby
Toothed Whales
-These include all the other cetacceans, including dolphins
-Because they have teeth they eat fish and squid
-The largest is the sperm whale
-The sperm whale was one of the most hunted
-Its head is full of whale oil which was used for burning lamps
-Sperm whales eat a lot of squid and undigested squid beaks and debris accumulate in their gut
-They then throw up large globs of it called ambergis
-Ambergis is an ingredient in expensive perfume
-A very popular toothed whale is the killer whale called an Orca
This is an optional but interesting video on why some orcas migrate
Porpoise Vs Dolphin
-A Porpoise is a small short nosed whale
-A Dolphin can be identified by its long nose called a beak
