Thursday, February 20, 2014

Lazy day company

I've been spending these rainy afternoons staring into my aquaria, tracking hermits and clams and anemones, peering behind weeds looking for mating amphipods, watching jellies and worms . . .

Here's a small sampler:

Very small hermit, under an odd-looking seaweed. I've been trying to identify these orange hermits, so far without success.

Eelgrass roots, covered with "gunk", mostly hydroids and detritus, with an amphipod. They love to feed on these messy roots.

Carnivorous snail, Nassa sp., following another up the glass, hoping to mate. When they're done, they'll both drop to the sand and burrow down out of sight again.

Amphipod on rotting seaweed, legs every which way, as usual.

Slipper snails, Crepidula sp., on one of the orange hermits.

The slipper snails are strange critters. Sometimes they sit for months on end in one place; one parked himself on a glass thermometer and stayed there, never moving more than half an inch either way, until I pushed him off to remove the thermometer. Others wander about, now showing up on a rock, now on a shell. They like the hermits, maybe because they are filter feeders, and the hermit is a messy eater.

A slipper snail starts out life as a male. If he finds a handy hermit with no other slippers in residence, he waits until another arrives and climbs on top. Then he undergoes a sex change to become female. All the other snails in a stack are male. They fertilize the eggs of the female on the bottom. When she dies, the male above her becomes female. The female is always the largest one in the stack.*

I have fewer than a dozen slippers (so far), so most of the "stacks" on these hermits are only 2 or 3 deep.

*In contrast, the female hermits are usually smaller; a quite large male will be seen dragging around a mate barely 1/3 his size. Amphipod males are also often much bigger than their mates. Since the other snails in my tanks are hermaphrodites, there is no size difference; each snail is male and female at the same time.

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