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                                    Order Pinnipeds 

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                                    Order Pinnipeds 

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Sea Lions, Seals, and Walrus
By: Nima Patel

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Millions of years ago, their ancestors lived primarily on land

Many of their features allow them to adapt to land and sea environments

Most of the time live in the sea but come on land to mate, give birth, shed, or take care their young ones

Most live in cold waters

Found in the northern and southern hemisphere

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Their molars are modified for consuming prey as a whole

Tail and external ears are small which limits dragging

All have fur which shed annually

Very good divers due to their reduced heart rate and high blood volume

Four webbed flippers which are used to propel their bodies

Large eyes and flippers helps moving in the water

All the organisms in this group contain blubber which is a layer of thick skin that keeps them warm in the cold waters and protects them

Their sensory organs are adapted to function in both air and water

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Order Pinnipeds is also known as Order Carnivora
Pinnipeds are aquatic carnivorous mammals
The more taxonomic names an organism shares shows how closely related they are

Seals, sea lions, and walruses all share the same order but different family which shows they are closely related but not the same species

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Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family:  Odobenidea
Genus: Odobenus
Species: O. Rosmarus

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They live in the Arctic waters (Canada or Greenland)

They follow the movement of the ice

Swim in water no deeper than 80 feet

Eat worms, sea-snails, shrimp, and fish

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The whiskers on the upper lip are used to detect and identify objects in the water, mostly pray

The walrus’s skin is thick and tough to help the walrus tusks attacks and protect from injuries

Use their hind flippers to help them move on land

They have tusks that are used for defense and to cut through the ice

No external ears

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Very social animals and travel in large packs

Establish dominance through their large bodies and displaying threats

Stay underwater for up to a half an hour

Males produce a bell like sound for courtship display

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Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Otariidae
Genus: Zalophus
Species: Wollobaeki

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Found in the Galapagos Archipelago island

When they are not in water, they are on sandy beaches with rocks

They can move quickly in water but not on land

Pointy, whiskered noses with a long and narrow muzzle

Powerful fins

Swims using its strong and developed fore flippers

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Very vocal and social

Males fight each other to prove dominance

Eat fish, octopus, and crustaceans

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Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Phocidae
Genus: Cystophora
Species: Cristata

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Live in the Arctic and North Atlantic oceans

Best survival rate is in colder climates

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They are blue gray with lighter undersides

Their limbs are smaller compared to the rest of their body but they are still powerful

They are excellent swimmers and divers

The name comes from the inflated hood on top of males heads

The hood is used as display for aggressiveness and to attract women

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Males will fight to display their dominance

They are independent animals for the most part except for the breeding and molting periods

Don't eat during these two periods

They mostly come out for food during the day

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The fossil records are from extinct organisms that show similar functions of the seals, sea lion, and walrus in modern day

Being able to survive on land and in water helps determine the evolution of the pinnipeds because it narrows it down from many organisms

A lot of the fossils are part of the face structure and skull, that shows how the have similar eating habits

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13-20 million years ago in the oligocene period

Lived in the eastern northern Pacific Ocean

Very small animal, similar to the Harbor Seal

It had more specific flippers and shows evolution from water to land

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7.25 million years ago

Has a similar structure of a leopard seal

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They are from the Miocene Period

Behavioral characteristics were very similar to the Northern Fur Seal

The males would use their strength to fight off prey

They are very similar to the seals and sea lions which shows the evolution through time

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Was around in the Miocene Period

It mostly lived on land but was able to swim

Used its webbed feet for walking and also as flippers when in water

Was classified as a seal once extinct

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Lived during the Miocene Period

Was more similar to a bear structure but also lived in the water

Scientist believe it lived during the phase in evolution where it was transforming for a land animal to also being able to swim

Its backbone portrayed a good swimmer

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Lived 5.3 million years ago

Walruses are similar to these due to their eating habits and similar face structure

This was the first sight of walruses

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This shows that the species in Order Pinnipeds are related to bears and dogs. They all share similar functions but use them in a different way

Raccoons and Weasels are also ancestors of seals, sea lions, and walruses

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The chromosome number in Order Pinnipeds will be either 32, 34, or 36
The similarity in chromosomes shows that the organisms are related in some way
Not having the same exact number of chromosomes shows that they are all different species
Walrus: 32 chromosomes

Male and female karyotype

Sea Lions: 34 Chromosomes
Seals: 36 Chromosomes

The karyotype shows that the inter breeding of the seals lead to diseases and infections that cause a mutations in the seals

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one chromosome that the seals, sea lion, and walrus all share is the canine genome

The canine is a certain type of teeth that help them survive in different ways

Either by catching prey or fighting

It is also seen in many other organisms

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The organisms in this group have many similar structures and functions
The way the organisms function are also very similar because they live in very similar habitats therefore have adapted to the same living conditions

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Comparing modern seals to the Puijila fossil there are many structures  that have evolved into the modern seal
Similarities

Head

Teeth

Spinal cord

Webbed toes

Heavy limbs

All these structures show that the land walking animal has evolved into the modern seals
The transformation of the feet for walking into flippers for swimming was similar in a different way because the same structure was used in different ways

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The development of their long spinal cord in all pinnipeds

this helps in the survival of living on the land and in the water

The development of their snout

helps with sensing smells when underwater

especially for walruses because they do not have external ears so it makes their hearing senses stronger

Many sea lions and seals will grow out of there tail but as seen in this picture they have a tail when first developing
Also seals and walruses will develop flippers in the first stages and continue to grow

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Looking at and comparing DNA can share a lot of information about the similarities and differences in seals, sea lions, and walruses because they all have little features that make them different species

DNA evidence has proven that seals and sea lions resemble each other and they both evolve from a common ancestor

The evidence that proves this similarity is showed in the mitochondrial unit and cytochrome B gene

As more research is being done by scientist, more evidence is being discovered leading them to believe that all pinnipeds shared a common ancestor at one point when evolving

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Divergent Evolution

Traced back years they all had a common ancestor

The Odobenidae (Walrus) and Otariidae (Seals & Sea Lions) diverged from the Phocidae family

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Gradual Equilibrium

They evolved over a long period of time

This is shown through the fossil evidence of walruses, seals, and sea lions

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Reproductive Isolation: properties are preventing organisms from interbreeding
Ex.  The ice caps limit the all three of the species from migrating to other areas and due to this they cannot breed with other organisms

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Evolutionary Mechanism: Non- Random Mating 

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Evolutionary Mechanism: Non- Random Mating 

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Non- Random Mating occurs in all three species

Males will chose who they want to mate and will display their strength to the women by fighting other males

They are attracted to each other based off traits such as color

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Darwin's Theory- Descent with Modification  

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Darwin's Theory- Descent with Modification  

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The traits were passed through offspring and this is show because they evolved from land dwelling animals to sea dwelling animals

A trait that was passed down from generations was the use of flippers for swimming and walking. At first they were every specific feet and then over time they became one but that trait was passed down for similar use

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Stabilizing Selection

They all have an advantage by having the trait to be able to survive on land and in water. Most animals cannot do this therefore they have an advantage

All have a thick layer called blubber that helps the survival rate go up in the cold weather

Walrus
Their tusks help them in survival to fight and to catch pray

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https://www.fws.gov/alaska/fisheries/mmm/walrus/wmain.htm

http://www.defenders.org/walrus/basic-facts

http://animaldiversity.org/site/accounts/information/Cystophora_cristata.html

http://animaldiversity.org/accounts/Odobenidae/

http://www.nhptv.org/wild/odobenidae.asp

http://www.palaeontologyonline.com/articles/2015/fossil-focus-seals-sea-lions-walruses/

http://www.arkive.org/walrus/odobenus-rosmarus/

http://placentation.ucsd.edu/walrusfs.htm

http://placentation.ucsd.edu/seal.htm

https://blogs.scientificamerican.com/tetrapod-zoology/pinnipeds-descended-from-one-ancestral-line-not-two/

http://palaeo.gly.bris.ac.uk/Palaeofiles/Pinnipeds/evolution.html

http://www.polarcruises.com/polar-info/antarctica-wildlife/seal-adaptations