Canis lupus hominis

As others have correctly answered, this is a leatherback sea turtle’s mouth.

Leatherbacks are the largest of all sea turtles, and they are also among the heaviest of all reptiles. The largest ones rival the saltwater/Indo-Pacific/estuarine crocodiles when it comes to body mass. The largest on record weighed over a ton.

This sea turtle is unique in that it doesn’t have a bony carapace. Instead, the top half of its body is covered with oily, leathery skin (hence the name “leatherback.).

They are also very unique among living reptiles in that they can generate their own bo dy heat, which is why these turtles are found in places like New Zealand and Norway. These turtles constantly move, and that continuous motion generates heat. They also have counter-current heat exchangers between the large front flippers and the core body and several counter-current heat exchangers around their their trachea. They also have a very thick layer of brown fat that prevents heat from escaping.

These turtles are easily the most adapted to a marine existence of all living reptiles. Their tear-drop shaped body is quite hydrodynamic, and the turtles’s front legs have become massive clawless flippers.  No other sea turtle is shaped in this fashion, and no other sea turtle has been able to live in so many different environments around the world.

These turtles eat almost nothing but jellyfish and salps. In Nova Scotia, lion’s mane jellies comprise 83-100 percent of their diets.

Because these turtles are endothermic and constantly on the move, they have to eat a lot of jellyfish all the time.

Having spikes in the back of the mouth and throat helps the turtle catch and hold onto its slippery prey.

When you realize these turtles can’t actually stop and hold something with their front flippers, the utility of such spikes becomes clear. The esophagus is similarly spiked, which prevents the jellies and salps from swimming back up.

These spikes are necessary to help the turtle catch enough jellyfish and salps to keep its massive body heated and in motion.

In case you were wondering what one of these turtles looks like, here’s a nice photo:

Leatherback sea turtles are currently quite endangered.

In 1980, there were an estimated 115,000 breeding females. Now, the population of breeding females is estimated to be as low as 26,000.

Leatherbacks are sometimes caught as bycatch in fishing nets, but they’ve never really been hunted by humans. The turtle eggs are sometimes eaten or used as aphrodisiacs.

The real problem they face is they have a tendency to bioaccumulate lots of toxins, and they are the turtles that will eat plastic bags and balloons.

These objects look very much jellyfish, so why would the turtle not want to eat them?

Too bad the turtles often get intestinal blockages from eating such things, and because they are wild animals living so far out at sea, an intestinal blockage is death sentence.

The leatherback is the last of the giant marine reptiles.

If it goes extinct, it will be the end of an era.

For millions of years, giant sea reptiles ruled the seas.

When this one goes, there will be no more.

The leatherback sea turtle lineage has existed in the ocean for an estimated 110 million years.

They’ve survived the mass extinction that took out the non-avian dinosaurs and most of the world’s crocodilians.

But they may be taken out by something no more complex than a plastic bag.