What Do Crustaceans Feed On?
Crustaceans are some of the more enigmatic creatures on the earth as many of them live deep underwater and are hard to reach. The word crustacean refers to sea-going creatures that have hard, chitinous shells instead of bones. They feed on a variety of things, depending mostly on the type of crustacean.
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Types
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The most commonly-known types of crustaceans are the crabs and lobsters. They are typical members of the family: they have multiple legs and hard shells, and live underwater. The family does also include shrimp and crayfish. These four creatures make up the majority of the crustaceans we know about, but this is not where it ends--the family also includes barnacles, wood lice and some types of plankton.
Predators and Scavengers
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The majority of crustaceans--most crabs and lobsters--are predators or scavengers. Their powerful claws are used to catch and kill prey, small fish or anything small enough for them to fight. The claw on the pistol shrimp, a very particular crustacean, is specialized to work like a weapon: it fires a bubble shock wave at its prey, stunning it. These animals spend most of their time in hiding, waiting for the right moment to strike.
If the hunting hasn't gone well, or if the opportunity presents itself, most crustaceans are also scavengers. The remains of a shark's meal or a fish that has died of old age and sunk to the bottom becomes a feast for whichever crustaceans manage to arrive on the scene and grab a piece first. This is also the case for woodlice, land-based crustaceans who eat decaying plant matter.
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Filter Feeding
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Barnacles at high tide. The barnacle is something of a black sheep in the crustacean family. Unlike its mobile cousins, barnacles set up home in a single place and feed on the microscopic plankton that washes through their airspace. At high tide, we see them on the shorelines, closed off and waiting for the water to return. This is when they open up their shells and dangle their feet in the ocean, feet covered in thousands of cilia, little hairs used to filter and trap plankton.
Parasites
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Copepods are another type of specialized crustacean. Unlike their cousins, these microscopic parasites will attach themselves to a host and stay there until the host dies. They are often found feeding on the eyes of smaller fish, like sprat, or sometimes attached to massive animals, like the whale. They are very simple animals, usually with parts dedicated to feeding and eating.
Special Case
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There is a class of shrimp, one of the most commonly cited cases of symbiosis, referred to as "cleaner shrimp." They are much sought-after by owners of tropical fish tanks because these tiny animals actually climb onto other fish and eat parasites and anything else that gets attached to the fish in its travels. These tiny animals wait in crevices, hiding from the handful of predators that go after them, but are recognized by fish who actually wait while the tiny shrimp cleans their body.
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References
- Photo Credit lobster image by Christian Schoettler from Fotolia.com barnacles image by Tiffany Cooper from Fotolia.com
