Whorl-Tooth Shark.

I'm making an exception, only because it's shark week.

This shark is actually extinct, so don't worry about crossing its path, unless you plan on getting in a time machine. I've debated whether or not to ever post extinct species, largely because of the forgotten diversity of things alive today, but I thought this would be a good one to post, if I ever broke that.

Very little is known about them -- they aren't really even sure what the shark looks like. Just know it is a shark and it has spiraled teeth. It may have looked nothing like a regular shark though, scientists are just guessing.

Their fossils are found in Utah, Idaho, and occasionally Wyoming and are about 280 million years old.

At first, scientists thought they were a tentacle of a sort for some strange animal, but then found several examples of this perfect form. Prompting them to believe it to be a structure. Under further investigation, turns out to be a row of shark teeth -- you might wonder, how are the inner teeth effective? They're just replacements. Only the top of the spiral is exposed, and when worn, the new teeth spiral in. Modern sharks have a similar mechanism, but rather than one spiral, the entire row of teeth swaps out (human teeth grow from under and push the others out, sharks rows of teeth rotate in).

What a bizarre shark.

Hatchet fish.

yea, yea, yea, they're not the prettiest fish in the world. But I assure you, while they lack in looks, they are extremely impressive animals. Here's why:

Camoflauge. This deep sea fish has many predators, but only a few that can find it. Partly because its mostly dark, but largely because it has incredible mechanisms for blending in. It has 2 ways of doing this:

1. Reflecting light. As you can see from the last picture, it has shiny scales. When turned away from a predator, it mirrors whatever color is beside it, making it essentially disappear.

2. Photophores. They have bioluminescent spots (like glow in the dark, but made with light-emitting bacteria) that are on the bottom of the fish called photophores and work in a mechanism called 'counter-illumination'. These photophores not only produce light, but they match perfectly the color of water above them, making predators below them incapable of distinguishing them swimming above from the ocean.

Other information: They live about 3600 m. below the surface of the water, and have eyes permanently fixed looking upward, suggesting that they eat things based on the silhouettes they leave, since the little light that exists comes from above. And based on its life cycle, it seems that they don't live longer than a year, typically.

Watch them and their camouflaging genius (start at about 6 minutes):

Whale Shark.

This wonderful giants are the largest of all living fish (it's not a whale). This shark is named so almost entirely based on its size. They can grow up to about 40 ft. and can weigh up to 15 tons (30,000 lbs!) and like elephants, they can live up to 60 - 70 years (reports estimate some might be over 100). Impressive, no?

Around the world, there are different names for them, most based on shapes on its back... in Kenya the story is someone threw shillings on its back, in other places the name literally means 'starts on its back' but my alltime favorite: "Ca Ong"... Vietnamese for "sir fish."

Their life cycle is also interesting. Typically, you hear there are 3 birthing classifications of animals... monotreme (they lay eggs), marsupial (pouch... animals are born premature) and embryonic (matured by mothers nourishment in womb). Whale sharks have something similar to the first and last of these types. They are ovoviviparious... meaning they have eggs, but they remain in the body, are hatched and followed by a live birth. This is different than embryonic because they are nourished through yolk in a closed egg, versus being nourished through tubes connected to the mother. They can give birth to up to 300 pups (yes, shark babies are called pups).

As large as they are, they are known for being gentle. The only injuries they have ever incurred on people are from accidental hits from its tail fin. In fact, they're normally playful with divers.

The other similarity they have to whales is their feeding -- they are a type of filter feeding shark (only 3 species in the world), meaning they eat krill, phytoplankton and occasionally small squid or vertebrates. Apparently when things bigger than that are caught and line the filter, they have been seen to 'cough' as a mechanism to clean the filter. A shark coughing is a funny image. They also swim really slowly... average top speed: 3.1 mph. They have quite a lot of weight to move, so I guess that's fair.

You can find them all over the world in the tropics.... Carribean, India, Africa, Japan, Hawaii, you name it. And they come relatively close to the shore, so if you are a diver, you can see them somewhat often if you are looking specifically for them.

There are a few places you can see them in aquariums... Japan, Taiwan, and the Georgia Aquarium.

Here's a wonderfully relaxing video from Okinawa aquarium in Japan (featuring other fish, too):

Mola mola.

Or more commonly known as the Ocean Sunfish. Pictures can barely capture the size of these fish giants. Average adults weigh in at 2,200 lbs. They are the largest bony fish in the world (some have cartilage).

The top picture is one from 1910 and weighs in at 3,500 lbs.
They have few known predators; sharks, orcas and sea lions. And people (let's just assume that's a predator for any animal I post, unless otherwise noted?). Their diet is pretty much strictly jellyfish, for some reason. And they live in the tropics. Since today is a busy day at work, that's all the info I'm putting up for today.

Mandarin Fish.

Easily my favorite fish. These live out in the Pacific and are named after the fact that their colors are vivid like the robes of Imperial Chinese mandarin. As you can see in the top picture, the female (left) has slightly different coloration than the male (right). But both are ridiculously cool.

If you ever find yourself in Chicago, they have these at the Shedd Aquarium. Probably a lot of other places, too, but that's the last time I remember seeing one.