Most species of hermit crabs have long soft abdomens which are protected from predators by the adaptation of carrying around a salvaged empty seashell, into which the whole crab's body can retract. Most frequently hermit crabs utilize the shells of sea snails, marine gastropod mollusks. The tip of the hermit crab's abdomen is adapted to clasp strongly onto the columella of the snail shell. As the hermit crab grows in size, it has to find a larger shell and abandon the previous one.
This habit of living in a second hand shell is what gave rise to the popular name "hermit crab", which is a reference to the idea of a hermit living alone in a small cave.
The Siamese fighting fish (Betta splendens), also known as the "betta fish" or just "betta", is one of the most popular species of freshwater aquarium fish. It is native to the Mekong river basin in Southeast Asia and called pla-kad or pla-kat ("Biting Fish") in its native Thailand.
Male and female Bettas flare or "puff out" their gill covers (opercula) in order to appear more impressive, either to intimidate other rivals or as an act of courtship. Females and males will display horizontal bars (unless they are too light a colour for this to show) if stressed or frightened. Females often flare their gills at other females, especially when setting up a pecking order.
Bettas are often kept in extremely small containers, a practice which many aquarists consider inhumane. This practice is due in part to practical considerations; few pet stores have the space or finances to display a large selection of male bettas except in small containers. However, many inexperienced fishkeepers still continue to house them in small containers after purchase. A popular misconception is that wild bettas live in very small puddles, and thus are "happier" when kept in cramped conditions. In reality, like any other fish, bettas are healthier, more active and will often grow larger when they are kept in a roomy tank. Aquarists typically recommend that there be at least 2 gallons (7.5L) for each betta, but 4 gallons (15L)or more is preferred.
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