#Genus: Zalophus

[haveyouseenthisanimal-irl]

[dread-doughnuts]

Skull Sunday 1: California Sea Lion

Welcome to the inaugural Skull Sunday! This is (what I hope will be) a weekly Scicomm post detailing a particular animal species utilizing skulls! This will be similar to some of my older posts on here, just on a more regular schedule with more pictures. The first species featured is the California sea lion (Zalophus californianus). All pictures are taken by me unless otherwise stated.

California sea lions are a species of eared seal and belong to the family Otariidae, which includes the other sea lions and fur seals. They belong to the genus Zalophus, which also contains the Galápagos sea lion (Zalophus wollebaeki) and recently extinct Japanese sea lion (Zalophus japonicus).

The species has a large range, stretching from southern Alaska to central Mexico. Three distinct populations are recognized based on the location of rookeries: the US stock (US/Mexican border through Canada), the Western Baja California stock, and the Gulf of California stock. This skull was collected in the Islas Coronados off the coast of Baja California.

California sea lions are a sexually dimorphic species. Males are generally much larger and more robust than females. Mature males also tend to display a pronounced sagittal crest and domed forehead. This particular skull is from a younger adult male, so it does not have a very pronounced crest.

Sea lions are piscivores, feeding primarily on fish and squid. Their typical dental formula is 3/2, 1/1, 5/5 (the first number being the top teeth and second number being the bottom teeth. Their teeth are used to grip onto prey and swallow it rather than cutting or chewing. Pathologies are somewhat common. This sea lion is missing one lower left molar and has a broken upper right canine.

While sea lions have keen underwater hearing they do not have the large auditory bullae that terrestrial carnivores have.

California sea lions are considered to be Lower Risk by the IUCN, though trends vary by population. The US stock is stable while the Gulf of California population has seen declines. Some fisheries in the US allow for limited culls due to the threat overzealous sea lions pose to endangered salmon.

California sea lions, like all marine mammals in the US, are regulated by the National Oceanic and Atmospheric Administration and are protected under the Marine Mammal Protection Act. This act makes it illegal to collect marine mammal parts under most circumstances. There are exceptions for Alaskan natives and scientific institutions.

This sea lion predates the MMPA being enacted, meaning that it is legal to possess. It was collected in 1961 and the MMPA came into effect in 1972. Specimens that predate the MMPA will need paperwork from NOAA to be legally possessed, which can be seen here! Names have been blacked out for privacy.

Thank you for tuning in to the first Skull Sunday! Check back next week for another installment with another species!

[rabbitcruiser]

California Sea Lions, Bronx Zoo

The California sea lion was described by René Primevère Lesson, a French naturalist, in 1828. It is grouped with other sea lions and fur seals in the family Otariidae. Otariids, also known as eared seals, differ from true seals in having external ear flaps, and proportionately larger foreflippers and pectoral muscles. Along with the Galápagos sea lion and the extinct Japanese sea lion, the California sea lion belongs to the genus Zalophus, which derives from the Greek words za, meaning "intensive," and lophus, meaning "crest." This refers to the protruding sagittal crest of the males, which distinguishes members of the genus.

Traditionally, the Galápagos sea lion and Japanese sea lion were classified as subspecies of the California sea lion. However, a genetic study in 2007 found that all three are in fact separate species. The lineages of the California and Japanese sea lion appear to have split off 2.2 million years ago during the Pliocene. The California sea lion differs from the Galápagos sea lion in its greater sexual dimorphism. The Steller sea lion is the closest extant relative of the Zalophus sea lions, being a sister taxon.

Source: Wikipedia

[amoebaetta]

The Cool California Sea Lion!

California sea lions are beautiful creatures that live on land and in the sea. Their ancestors were predominantly land animals but they have adapted so that they come on land to relax, mate, and have their babies. California sea lions are also commonly known as Galápagos sea lions. They live on the rocky west coast of the Americas.

They spend most of their sea time hunting for fish, squids, and octopuses. California sea lions, or in their scientific name, Zalophus californianus, are carnivores. They eat approximately 5% - 8% of their body weight every day. Their entire source of food is from the sea, and they spend about fifteen or sixteen hours hunting. These hunting trips often include 85-200 dives. Male California sea lions go through a fasting period during their mating season, so as to protect their mates. They occasionally may go to the water to drink during this fasting period, but otherwise all their water comes from the food they eat, which is not eating like it is to us. They swallow their food whole, or maybe tear the food into chunks. One thing scientists find strange about these creatures is how they swallow stones. They may do this for weight balance or to get rid of stomach irritations, but in truth they may just like to eat stones.

Theories about the ancestors of the California sea lions vary. Some scientists look at the evidence that is available but some look in the gaps at what isn't. One thing that all can agree on though is that 23 million years ago the ancestors of the modern sea lion were there. California sea lions did not undergo a heavy evolution though. It is believed that they were previously only land animals but adapted to go into the water for food, or that they adapted because of climate changes in their areas. The ancestors were thought to be good swimmers too, but with not such incredibly powerful flippers. The size of the California sea lion was probably also not so large. Today the male California sea lion is up at eight feet long and eight hundred and fifty pounds, but their ancestors probably were the size of our today otters.

Male California sea lions come up on land to mark their territory and prepare for the females to come up to shore in May. The males are mature enough to breed when they are six years old but most do not begin until they are ten years old so that they will be large enough to scare away other potential rivals. These males will bark more aggressively and will fiercely protect their females from harm. It is not uncommon for them to have up to thirty females that they will breed with. The females come up to the shore already pregnant from the breeding season last year, as their gestation period is about eleven months. They give live birth to their pup, and they generally only have one pup or rarely twins, and then this pup immediately begins drinking their mother's milk. This milk has over fifty percent of the nutrients the pups need to grow, so their growth period is extremely fast. The female will mate again in about thirty days, leaving only about a month in the entire year that she is not pregnant. The pups will grow blubber from this milk and the fluff from this blubber will be shed by the time that they enter the water with their mother for the first time. For the pups’ first six months they are very vulnerable and can be trampled by the herd or they will be eaten by bigger predators. Instinctively these pups know how to swim, but they must be taught how to hunt and how to hide from larger predators.

The taxonomic classification is, in order:

Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Pinnipedia Family: Otariidae Genus Species: Zalophus californianus

The California sea lion is very playful and friendly. They are such intelligent creatures that they can be trained to do tricks for treats. They do not have a set social order during the non-nation seasons, but love to lay with or on top of each other. During mating season though, the males are aggressive towards other males. The pups are perhaps the most playful though, riding the surf and pushing each other around while they play. These California sea lions are like humans, in that they have group panics sometimes. When a loud sound is made, they rush together as a group towards the water. When it is not mating season though, they do not have these group panics as much.

The California sea lion is an amazingly intelligent creature, and should be treated as such. Thanks for tuning into etta’s science! 

~Sources~

https://seaworld.org/en/animal-info/animal-infobooks/california-sea-lion/behavior

https://seaworld.org/en/animal-info/animal-infobooks/california-sea-lion/diet-and-eating-habits

http://www.sealion-world.com/sea-lion-evolution/

http://www.sealion-world.com/sea-lion-reproduction/

https://seaworld.org/en/animal-info/animal-bytes/mammals/california-sea-lion

http://www.marinemammalcenter.org/education/marine-mammal-information/pinnipeds/california-sea-lion/

[eanthony24-blog]

Zalophus californianus is the scientific name for the sea lion. Its Kingdom is animalia,phylum chordota,class,mammalia,order pinnipedia,family  otariidae, and genus and species is Zalophus californianus.Sea lions have long torpedo shaped bodies that are suitably adapted to glide them through the water. They are also able to move around easily on land. Males are considerably larger than females. Males are very large and can weigh from 1,500 pounds up to 1 ton. They can measure up to 12 feet in length. Female sea lions are much smaller with a weight of 700 pounds and average about 9 feet in length.Sea lions do not have very good eyesight and it is believed that they are nearsighted. There is evidence to indicate that Sea Lions can see better in the water than they can on land.Sea lions are found in large colonies and are very social animals.Female Sea Lions are pregnant when they come to shore to mate again. The female will give birth and then mate again for the next season within a couple weeks.Sea lion are indangered species but are being conserved. The sea lion had killer whales and great white sharks as their predators.When sea lions come in contact with humans they can contract many health problems resulting in death.They eat fish,squid, and octopus.They live in rocky and sandy beaches and range from British Columbia to Mexico.

https://animalcorner.co.uk/animals/sea-lion/

https://seaworld.org/Animal-Info/Animal-Bytes/Mammals/California-Sea-Lion