Crustacean Pictures

Mantis Shrimp, Ghost Crabs, Coconut Crabs, and More

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Mantis Shrimp

A mantis shrimp peers out from the opening of its den.
A mantis shrimp peers out from the opening of its den. Photo © Gerard Soury / Getty Images.

Mantis shrimp (Stomatopoda) are a group of malacostracans that are notable for their extraordinary visual system. The number of different cone receptors present in the eye of a mantis shrimp far out-numbers that of even humans—mantis shrimp have 16 types of cone receptors while humans have just three. This elaborate system of receptors in the mantis shrimp's eyes gives them the ability to perceive colors across a wide spectrum of wavelengths as well as polarized light.

Mantis shrimp are also known for their specialized claws, which enable them to smash or spear their prey with great speed and force. There are approximately 400 species of extant mantis shrimps. Members of the group are solitary marine invertebrates that burrow into sediments or hid in crevices between rocks. They rarely hunt their prey and instead wait for prey to wander past as they lie in wait.

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Ghost Crabs

Atlantic ghost crab
Atlantic ghost crab. Photo © Danita Delimont / Getty Images.

Ghost crabs (Ocypodiane) are a group of crabs that live in tropical and subtropical coastal regions throughout the world, where they can be found foraging on sandy beaches and in intertidal zones. Ghost crabs are nocturnal animals that hunt small animals and scavenge carrion and plant debris. During the day, they remain in their burrows.

Most species of ghost crabs are pale in color, while others have the ability to alter their color to mimic their surroundings. They do this by changing the distribution of pigments in their chromatophores. A few species of ghost crabs are more brightly colored.

Ghost crabs have long eye stalks with a large cornea located on the bottom part of the eye-stalk. Some species have horns on their eye stalks. Their carapace is almost rectangular.

There are 22 species of ghost crabs that are classified into two groups, the Ocypode (21 species) and the Hoplocypode (1 species). Members of the Ocypode include African ghost crabs, horned host crabs, golden ghost crabs, western ghost crabs, tufted ghost crabs, painted ghost crabs, Kuhl's ghost crabs, and many other species.

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Coconut Crab

Coconut crab - Birgus latro
Coconut crab - Birgus latro. Photo © Rainer von Brandis / Getty Images.

The coconut crab (Birgus latro) is a terrestrial hermit crab that holds the distinction of being the largest living terrestrial arthropod in the world. Coconut crabs can grow to a considerable bulk, weighing as much as 9 pounds and measuring up to 3 feet from tip to tail. Coconut crabs reach this considerable size by eating nuts, seeds, fruit, and other plant materials. They also occasionally feed on carrion. Coconut crabs have earned their name for their tendency to climb coconut trees and to dislodge coconuts, open them, and make a meal out of them.

Coconut crabs are found on islands throughout the Indian Ocean and central Pacific Ocean. They are most numerous on Christmas Island, although they are there out-numbered by their cousins the Christmas Island red crabs.

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Barnacles - Cirripedia
Barnacles - Cirripedia. Photo © Karsten Moran / Getty Images.

Barnacles (Cirripedia) are a group of marine crustaceans that includes about 1,200 species. Most barnacles are sessile during the adult stage of their life cycle and attach themselves to a hard surface such as rocks. Barnacles are suspension feeders, they extend their legs into the surrounding water and use them to direct food particles such as plankton into their mouth.

The life cycle of a barnacle begins as a fertilized egg that hatches into a nauplius, a free-swimming larval stage that has a single eye, a head and a single body segment. The nauplius develops into a second larval stage, the cyprid. During the cyprid stage of its life cycle, the barnacle locates a suitable place to attach to. The cyprid adheres to the surface using a protein compound and then transforms into the adult barnacle.

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Water flea - Daphnia longispina
Water flea - Daphnia longispina. Photo © Roland Birke / Getty Images.

Daphnia are a group of freshwater planktonic crustaceans that include more than 100 known species. Daphnia inhabit ponds, lakes, and other freshwater habitats. Daphnia are tiny creatures that measure between 1 and 5 millimeters in length. Their body is covered by a translucent carapace. They have five to six pairs of legs, compound eyes, and a pair of prominent antennae.

Daphnia are short-lived creatures whose lifespan is rarely more than six months. Daphnia are filter feeders that consume algae, bacteria, protists, and organic materials. The propel themselves through the water using their second set of antennae.

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Micrograph of a copepod.
Micrograph of a copepod. Photo © Nancy Nehring / Getty Images.

Copepods are a group of tiny, aquatic crustaceans that measure between 1 and 2 millimeters in length. They have a rounded head, large antennae, and their body is tapered in shape. Copepods are diverse, with over 21,000 known species. The group is divided into about 10 subgroups. Copepods inhabit a range of water types, from freshwater to marine. They are found in many different habitats, including the waters inside subterranean caves, pools of water that collects on leaves and forest floors, streams, lakes, rivers, and open ocean.

Copepods include species that are free-living organisms, as well as those that are symbiotic or parasitic. Free-living copepods feed on phytoplankton such as diatoms, cyanobacteria, dinoflagellates, and coccolithophores. They play an important part in the food chains they belong to by linking primary producers such as algae with higher levels of the food chain such as fish and whales.

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Fairy Shrimp

Fairy shrimp - Anostraca
Fairy shrimp - Anostraca. Photo © Fabrizio Moglia / Getty Images.

Fairy shrimp (Anostraca) are a group of crustaceans that includes about 300 species. Among the best-known groups of fairy shrimp are the brine shrimp.

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Caribbean Spiny Lobster

Caribbean spiny lobster - Panulirus argus
Caribbean spiny lobster - Panulirus argus. Photo © Steve Simonsen / Getty Images.

Caribbean spiny lobster (Panulirus argus) is a species of spiny lobster that has two large spines on its head and whose body is covered with spines. The Caribbean spiny lobster does not have claws or pincers.

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Hermit Crab

Hermit crab - Paguroidea
Hermit crab - Paguroidea. Photo © Brian T. Nelson / Getty Images.

Hermit crabs (Paguroidea) are a group of crustaceans that inhabit the abandoned shells of gastropods. Hermit crabs do not produce their own shell, instead, they find an empty shell that they insert their spiral-shaped abdomen into for protection. Hermit crabs most often select the shells of sea snails, but occasionally they might also use empty bivalve shells for shelter.

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Shield Shrimp

Shield shrimp - Lepidurus
Shield shrimp - Lepidurus. Photo © Clive Bromhall / Getty Images.

Shield shrimp (Notostraca), also known as tadpole shrimp, are a group of crustaceans that have an oval, flat carapace that covers the head and body and numerous pairs of legs. Shield shrimp range in size from 2 to 10 centimeters in length. They inhabit shallow puddles, pools and lakes where they feed on invertebrates as well as small fish.