Tuesday, January 21, 2014

Favorite Vertebrates

Hello everyone! Sorry if this is super long, you can skip the intro straight to the list if you want.

Now, I could buck the trend of my last several posts and not talk about animals/biology, but I don't feel like it. Also, animals and life are fun and interesting.

So stewing in my mind the last several weeks was the idea for a blog post on my favorite animals from each class of the kingdom Animalia. This came about because of thinking about how people use the word "animal" in non-inclusive ways. Some people think they can be vegetarians and still have fish (and some don't even mean piscitarian, oddly enough- they have that assumption that fish don't count because they've got bug eyes and aren't cuddly). One book, when speaking about list about the coolest animals appearing in scripture, said that bees technically weren't animals, but they'd count them. And my first thought was yes they should count them, not because they're cool (which they are) but because they actually are animals. Incorrect definitions of the categorical term "animal" are used all the time: insects aren't included, birds aren't included, humans aren't included. If only there was a way that we could have a word that was what they meant when they said animal. And there are those words, but they're not common knowledge and come from the science of biological classification. Therapods, for instance refer to birds, reptiles, amphibians, and mammals, leaving out fish, worms, sponges, insects, etc. etc. etc.

Although complicated, classification can be fun if you're into it. And so I had this idea to combat this misappropriation of the word animal (which I don't know why I'm doing it on this site, and know all of you don't use it in inappropriate ways), I was going to make a list with my favorite animals from each class. I chose the class level because, between birds, reptiles, fish, amphibians, and mammals, I couldn't make up my mind as to my favorite vertebrate (the phylum containing those classes). I thought it would be a hard, but manageable, task.

Unfortunately I was right about the first part, but the later adjective may be incorrect.

See, Animalia contains thirty-six phylums (at the moment). However, Animalia contains 111 extant classes currently, and that's not including extinct classes (you can see them here). Only seven contain what are traditionally thought of as animals (fish, birds, reptiles, amphibians, and mammals).

Because of this, this post will ironically include my favorite animals from each class of Vertebrata. Maybe later I'll move through the other thirty-five phylums.

Agnatha (jawless fish)
For agnatha, I had to choose between the lamprey and the hagfish, and I believe the hagfish takes the cake. I am choosing the type specimen for the group, the Atlantic lamprey, not only because it's from the closer ocean but also because its scientific name, Myxine glutinosa, comes from its slime. Slime is produced from its body as a defense mechanism, thought to cover the gills of predatory fish, making them unable to breathe, and thus hagfish have few predators. They also will tie themselves in overhand knot to scrape the slime off, and can produce several liters of slime at a time from their body, which is much smaller than several liters. In terms of eating, since they have no jaws, they feast on carcasses and enter soft tissues and holes like the mouth, eyes, and anus. They are also known to do this to sick or injured fish, basically entering a wound and eating the dying fish from the inside out. Gross, but kinda cool.

Chondrichthyes (sharks, rays, skates, and ghost sharks)
Now, there are a lot of contenders for this one. However, based both on its cool appearance, interesting life history, and status as a "living fossil" (meaning they must be doing something right,), the frill shark (Chlamydoselachus anguineus) comes out victorious. Just look at the picture and see if you don't instantly love it. They are described as sharks that look like eels. They have roughly 300 hundred teeth, which grow in terrifying rows. They are also viviparous, meaning their young are hatched from their eggs before they are born from their mother. Though they subsist mainly on yolk, the mothers give their young nutrients through some other as yet unknown means.The mothers also have the longest gestation period of any known animal, three and a half years. They have not been known to ever hurt anyone, asides from scientists accidentally cutting themselves while examining their teeth.

Osteichthyes (bony fish)
Also considered a "living fossil," my favorite bony fish happens to be the coelacanth (specifically the West Indian coelacanth, Latimeria chalumnae). Its status as a living fossil is currently contested, as recent studies have shown the diversity of the two species is greater than previously believed and that previous studies showing low diversity were biased. The two species comprise the most endangered order of animals, as the West Indian coelacanth is critically endangered and the Indonesian coelacanth is threatened. Coelecanths have no commercial value, as they taste terrible, except for as museum specimens (a demand which has made other species go extinct in the past). They also are lobe-finned fish (fish with a bit of an "arm" to their fin), and retain their notochord, which most vertebrates lose during embryonic development. Their braincase is also only 1.5% tissue, the remaining 98.5% being fat.

Amphibia (amphibians)
The eastern newt, Notophthalmus viridescens, is my favorite amphibian, not the least because of its dramatic changes throughout its life. It begins as a larva with gills which cannot leave the water. Then it becomes an adolescent, known as the red eft, which is bright red/orange, with black spots and orange spots bordered with black. During this stage it lives on land and has dry skin, which is uncharacteristic of amphibians in general. These efts travel far, to other bodies of water to keep high genetic diversity among populations, and they are also very bold. When it becomes an adult it becomes a dull green-brown, grows a wider tail, and becomes almost completely aquatic, with wet skin once again. It does, however, retain the orange spots. These newt also can home (move to an original location through unfamiliar areas) using magnetic orientation.
Red Eft

Reptilia (reptiles)
Of the reptiles, I find the marine iguana, Amblyrhynchus cristatus, to be one of the most interesting. Ordinarily reptiles are not found in ocean waters, asides from sea turtles and sea serpents. Unlike sea turtles and sea serpents, which are almost completely aquatic, the marine iguana is still terrestrial. The live on the Galapagos Islands, where they have no natural predators, and spend a lot of their time basking on the beach. The marine part of their lifestyle comes when they want to eat. They graze on seaweed along the coast of the islands, and the end of their snouts have even become flatter to better accommodate grabbing the plants. They can dive up to 30 ft (9 m) to reach the seaweed, and they have to bask after a dive to return their body heat to normal. During an El Nino cycle, when the amount of seaweed decreases, the iguanas actually decrease in length by up to 20%, as small iguanas will heat up faster in the sun and thus are able to do more dives for food. It is not known how exactly they decrease their length by such a large amount. They actually are related to the Galapagos land iguana, and form fertile hybrids occasionally at the edges of the beach.

Aves (birds)
There are many birds I like, and it is hard to choose just one to love. But since it's simply my favorite, and not my one-and-only-favorite, it was pretty easy. Most of you probably already know this, but I like talking about it. The secretary bird, Sagittarius serpentarius. This bird looks like an eagle crossed with a small crane, which results in an epic looking bird. Their name comes from the Arabic saqr-et-tair, which means hunter-bird, and not because the black crest feathers look like pencils behind the ear of a secretary, as most people think. They're the only bird in their genus and family, and feed primarily on snakes, as well as other small reptiles, mammals, insects, and  birds. They chase their prey on foot and then beat them with their feet or beak before tearing into their  flesh.

Mammalia (mammals)
I could say people in this category, but I feel that would be based too much on intrinsic biases (also, there are so many other cool animals to choose from). So I'm going to choose naked mole rats, Heterocephalus glaber (even if people were in the running I would still choose naked mole rats). Even though they're not cute, even though they're about as far away you can get from cute without being a rotting corpse, they're cute in the ugly way. If you want a cuter name than naked mole rat, you can call them the sand puppy. Anyway, they live underground in a hive and have a highly hierarchical society. Dominated by a queen, the females are all larger than the males, and so the males are at the bottom rung of the social ladder. The queen is the largest, and regularly goes around the tunnels intimidating the subjects and releasing pheromones to keep them subordinate. When the old queen dies, the strongest females fight to the death to become the new queen. The winner's spine will spread out (increasing the space between vertebrae), making the back weaker but the female larger. They also do not get cancer and don't age as fast as other mammals, likely due to the production of the super-sugar Hyaluronan that causes their skin to be loose. Interesting, huh?

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