Mollusc Week: I've saved the best for last.

Hoo boy, it's been a weird week. Molluscs are strange creatures in general, and picking out exceptionally strange or obscure ones makes them look even weirder. Cephalopods are slowly taking over the world. So, what could possibly top flying squid?

Tell me if this doesn't sound like crack to you: Antarctic oysters that can change sex.

Belongs to the Smithsonian. Yep, that's an oyster, all right.

Lissarca miliaris is far from an impressive oyster.  It's small, unassuming, and lives in a place that most sane people would dare not venture to. If it involves Antarctica and not penguins, people just plain won't go; this says nothing about one's willingness to dive beneath the ice for shellfish. Again, not penguins. Only marine biologists acknowledge this thing's existence.

These weird little oysters follow the same reproductive strategy that tunicates and some fish have: they start out as fertile males, then mature into egg-bearing females. They may also go back to being males when brooding their young. At first, researchers were only looking at breeding females; then they found males with the mollusc equivalent of "junk" as well as eggs. Yep, these little molluscs are genuine, natural, breeding hermaphrodites.

Of course, there is a natural advantage to changing sex. Antarctica is a harsh environment.  The more viable mating partners there are, the better; mating at a young age is also a good idea in such an environ. These oysters have all the reason in the world to be natural transexuals. Why should we think of them as freaks for it?

So yeah. There's your awesome week of molluscs! They solve mazes, stick really hard to rocks, fly, and now change sex! A few of them also taste terrible, but most of them can be seen at your local sushi bar. In case of mollusc world takeover,  prepare the tempura batter and chopsticks.

Creature Feature: Elephant Seal.

If you haven't noticed, there are some groups of animals I just tend to...avoid. As stated in my ribbon seal entry, pinnipeds are one of those groups. That's kind of a shame; plenty of them are strange enough to warrant entries. Some people would consider the simple fact that seals and whales are not related at all mind-blowing. (For those curious: Whales are related to ungulates such as pigs, sheep, and cattle, whereas seals are closer to other carnivorids.) That said, I'm not kidding: some seals really are that weird.



Elephant seals (Mirounga) come to mind as the weird seal. Most seals are at least slightly cute, especially as pups; they have that adorable baby mammal face that yields a collective "awwwww." There are two species of elephant seal, both of which sport the signature nose.  They eat fish and cephalopods - no surprises there. One (the Southern elephant seal, M. leonina) lives in the Antarctic Circle; the other (Northern, M. angustirostris) can be found around the lower part of California. How this happened, I have NO idea.

Nature does not give seals weird noses just to make humans freak out. The elephant seal's funny nose has two distinct, equally-awesome functions. One use is to amplify the male seals' roar; this theoretically keeps weaker males away from the big guy's harem of 40-50 females, but many encounters get bloody regardless.The other use is to help them conserve water; male elephant seals do not leave the beach during the entirety of mating season, so they conserve some moisture from every breath in that nose. If you had a harem of 40 women, you wouldn't leave the beach, either. Admit it.

"Hey, baby...room for one more..."

Not only do the males of the species have those weird noses, but Southern elephant seals are the largest seals in the world. Females get around 10 feet; males get around 20 feet from head to tail. They can weigh up to 4,000 kg or 6.600 pounds- take your pick, both of those numbers are in the thousands. They really do earn that "elephant" title.

These seals have one more stunning thing about them: They are the best divers of any mammal, discounting dolphins and whales. Thanks to a special stash of myoglobin, the elephant seal can stay underwater for two hours. They dive up to 1550 meters below the surface to search for food. Although they aren't related to dolphins and whales,  the elephant seal may be an evolutionary step in that direction.

(For the record, by the way: National Geographic has politely informed me (i.e. asked for a donation by telling me) that there are now officially more tigers in captivity than there are in the wild. Again, I'm not saying this is a good thing - wild tigers are still awesome - but given that the areas with said tigers probably have some corrupt politics going on preventing the wild tiger population from flourishing, isn't it good that we have a plan B?)

Creature Feature: Scenella.

Hello, and welcome to another entry set in the Cambrian shallow seas. Before we start today's entry, we would like to remind you all that this blog does not condone the use of psychoactive drugs. That means that everything we post from the Cambrian Period definitely existed. We're sorry if this disappoints any of you.

That said, mollusks with hats.

 

Scenella was one of several strange mollusks in the shallow Cambrian seas. It has been found in Asia, Antarctica, Europe, and North America. There have also been some theories that it was related to floating hydrozoans like the Portuguese man-o'-war, although several things say it's an ancient mollusk. 

Scenella were small, shelled creatures. They often hung around in groups if the Burgess Shale is any indication. They were probably eaten by larger, faster things like Opabinia and Ottonia - both of which are trippy in their own right. Scenella themselves probably ate algae and small bits of debris. In other words, they were the zebra mussels of their time.



Despite probably bearing many similarities to small, modern mollusks, Scenella remains strange. That hat-like shell makes it look like an ancient limpet (which probably could use an entry in and of itself), which would line up with it being a mollusk rather than an oddly-developed hydrozoan. An affinity to gastropods (snails and slugs) is likely due to how the muscles were attached. Show me the evidence for these guys being hydrozoans and we will gladly hear you out.

Remember, kids, seeing things out of your nightmares and acid trips on this blog is A-OK. It's all right in museums and labs, too. If, however, you are walking along and see a troupe of hat-wearing mollusks crossing the road, you may wish to see a shrink.