Crustaceans include crabs, shrimps, lobsters, crayfish, barnacles and form the majority of planktons throughout the oceans. Formerly included in the Phylum Arthropoda, this group was raised to the phylum status after detailed anatomical studies. The body is usually divided into a head with two pairs of antennae (in contrast to only one of the arthropods), a thorax and an abdomen, both with paired appendages, which are usually branched limbs. Crustaceans are able to cut an injured limb and eventually regenerate it. Gills are present in many of them, but the smaller forms respire through their body surfaces.
Two types of lobsters are conspicuous on Philippine reefs: the spiny lobster, Panulirus, and the distinctive slipper lobsters, Scyllarus and Parribacus, which have wide flattened tails and bodies. All are occasionally observed in shallow areas, under coral heads, but normally at depths greater than 10 meters. Like most crustaceans, lobsters are much more active at night than during the day. After molting, lobsters show a craving for calcium carbonate or shell matter. At the base of each large antenna the spiny lobster has a stridulating (noise making) apparatus. It is apparently triggered only when the lobster is molested and may be used to ward of predators, particularly fish. Most species spawn every other year.
More than 240 species of pontoniine (commensal) shrimp are reported from the waters of the Indo-Pacific.
Phylum Crustacia (Crustaceans)
Class Malacostraca (Crabs, Lobster, Shrimps) This group composes three quarters of all crustacean species. The entire group is of considerable importance both biologically and as a food for humans.
Order Decapoda (Shrimp, Crab, Lobster, Crayfish)
Family Palinuridae (Spiny Lobsters)
Panulirus Versicolor Sp. (Painted Spiny Lobster) Boldly patterned. The abdominal bands are wider than that of those of P. Marginatus. The white and tan pattern on the carapace is distinctive. The antennae are white, and conspicuous, and the legs have several bold white or blue stripes. Nocturnal, hiding in crevices during the daylight. (1) (2)
Order Stomatopoda (Mantis Shrimp) The stomatopods or "mouth footed" shrimps are named for their eight pairs of appendages modified for mouth parts. Also known as mantis shrimp, as they resemble the praying mantis in shape and in their method of eating. Mantis shrimp have a "jackknife claw" with an end segment that fits into a groove in an inner segment, just as a jackknife blade fits into its groove when closed. Has been known to inflict wounds on human fingers.
Family Squillidae (Large Mantis Shrimp)
Odontodactylus Scyallarus Sp. (Mantis Shrimp, Smashing Mantis Shrimp) Among the most colorful of reef animals. It is easily distinguished from other mantis shrimp by its bright green body color, blue head and re orange antennae and thoracic limbs. The eyes are spherical in shape and are divided by two parallel lines through their center. It is a night feeding carnivore. Sand and rubble bottoms. Depth to 70m.
Family Palaemonidae (Commensal Shrimps)
Periclimenes Brevicarpalis Sp. (Anemone Shrimp) Commensal Anemone Shrimp. Distinguished by large white spots, the spot on the head giving the appearance of a wart of hunchback,. The tail has five large black spots with orange centers. Length 4cm. Is frequently sighted on sea anemones and is generally transparent with characteristic colored spots. (1)
Family Rhynchocinetidae (Hinge-Beak Shrimp)
Rhynchocinetes Durbanensis Sp. (Duban Hinge-Beak Shrimp) Similar in coloration to and commonly reported incorrectly as R. Uritai, this species differs by its very long rostrum. The rostrum bears spines along the entire upper edge, culminating with 9-10 tightly spaced spines at its tip and 16-18 spines along the underside. The species also differs by the bold red and white patterns on the body. The white inner line of the red stripe is not broken and very bold, as wide as the red lines. The angle of the main stripes on the abdomen also differs. Lives deep in crevices and holes. Usually occurring in large numbers together. (1) (2)
Family Hippolytide (Cleaner Shrimp)
Thor Amboinensis Sp. (Anemone Shrimp, Squat Shrimp) Cleaner shrimp has distinguishing white spots and is found to live with anemones worldwide. It is a mall brown shrimp that has a saddle of large opalescent spots on its thorax and abdomen. These spots are encircled by a thin purple outline. Similarly colored spots occur at the base of and on the tail, on the abdominal plates, and on the eye stalks. Individuals hold their tail almost vertically. Commensal on corals and a number of anemone species. Usually observed in pairs, but you may find as many as 6-8 on a single host. Females are nearly twice the size of the male. (1)
*Reference: Philippine Coral Reefs A Natural History Guide By Alan T. White & Coral Reef Animals Of The Indo-Pacific By Terrence M. Gosliner, David W. Beherens, Garry C. Williams
*Photos: Are Full Moon Divers. All Rights Reserved.