Showing posts with label freshwater. Show all posts
Showing posts with label freshwater. Show all posts

Tuesday, February 5, 2013

Creature Feature: Apple Snail.

I apologize in advance for the video I am about to show you:



Yes, snails can actually be interesting to watch. I had the pleasure of seeing one of these up close and active. These are apple snails (family Ampullaridae), and they are among the most popular freshwater aquarium snails in the trade. The 6 genera in the family can be found in the freshwater areas of South America, Europe, Africa, Asia, and the lower parts of North America.  They are also marketed as "mystery snails," which is a complete marketing gimmick. These snails are far from a mystery, but still quite cool. We'll focus on Pomacea for now; other apple snails are fascinating in their own rights.

Apple snails are among the few truly amphibious snails. They have both primitive lungs and gills.  The mantle - the part of the body that yields a shell - is actually divided between the two types of respiration. Thankfully, most apple snails can stay aquatic; only if food runs out in the water will they move onto land. They have survived for over 50 million years for a reason.

The shell even looks apple-y.


That said, if you intend to breed apple snails, it is not as easy as it is with some other snails. Unlike most snails, apple snails have sexes - they aren't hermaphrodites. Each species of apple snail has its own egg-laying style and preferences, so adjust accordingly. We wish there was a cute Valentine's Day pic with snails, but these guys and girls sound difficult to sex properly.  If taken care of, some snails can get shells up to 6 inches in diameter.

Apple snails have mixed effects when introduced to non-native ecologies. In Taiwan, apple snails were marketed as a protein source, but fell flat on their not-faces and escaped into the wild after being unprofitable. The population then exploded; remember, these are versatile, adaptable creatures. Before they were bred in captivity, many apple snails were actually unwelcome hitchhikers in aquaria. Times change.

 Other people deliberately introduce apple snails (but not Pomacea) to out-compete and even eat more harmful snails that are vectors for parasites - some deadly, some just annoying. They are even eaten in Mexico. Mystery snails no more; apple snails are here to stay, but we make no promises about keeping the doctor away.

Saturday, September 11, 2010

Creature Feature: Bdelloid Rotifers.



Back in microbiology class, we looked at some pond water beneath a microscope. Among our fauna to look for were rotifers- single-celled animals so named because of their circular mouths ("rota" meaning "wheel" in Latin). That, and they swim around as though they are driving little cars.


This little thing is like Speed Racer on drugs, swear.

I had no idea that rotifers had such interesting sex lives...or lack thereof.

Bdelloid rotifers do not have sex. At all. They have not had sex for 80 million years.

This is not the first time that parthenogenesis (yes, all rotifers are female) has come up on this blog. It was especially common during Lizard Week. Many invertebrates can self-fertilize, reproduce simply by being cut in half, or have the junk of both sexes. Animals have some pretty damn freaky ways of mating, so hearing about something that just doesn't get it on period is unusual.

More importantly, how does that work?

One of the main benefits of sexual reproduction is that, in the process, genes mix. This allows for new mutations to pop up every now and then that allow a species to become more or less fit for survival. For an asexual species to not only populate but thrive, there had better be a pretty damn good substitute for gettin' jiggy with it.

They have one. Actually, they have two.

Bdelloids steal genetic material from other organisms. These genes are fully functional; if the original bearer of that gene was poisonous, the rotifer will be, too. Gene swapping is common in bacteria but rare in animals. If it were more common, we'd all be plastic surgeons stealing each other's awesome hair, racks and other talents.


In humans, this has horrible results.

These rotifers are also very hard to kill. They can survive being dehydrated - sometimes even giving birth while in the same state as a Frito−Lay product. Also, out of all the animals in the world, they are the MOST capable of surviving radiation. Hail your new overlords: Rotifers and cockroaches!