TAXONOMY

KINGDOM      Animalia

PHYLUM        Arthropoda  (External skeleton, segmented body and jointed appendages)

SUBPHYLUM  Crustacea

CLASS          Malacostraca

ORDER         Decapoda  (ten legged)

FAMILY        Hippidae  (mole crabs or sand crabs)

GENUS/SPECIES  Emerita analoga

 

GENERAL CHARACTERISTICS

 Grey or sand colored exoskeleton without spines or claws.  The eyes are on long stalks and the antennae are also elongated so as to project above the surface of the sand. The legs and uropods have hairy margins to assist in digging and for use in collecting food and transferring it to the mouth.  The first pair of antennae reach above the sand for respiration, and the second pair, resembling feathers, are extended when the crab feeds. The female is nearly twice as large as the male up to 35 mm  (1.4 in) long and 25 mm (1.0 in) wide.

The sand crab always moves backwards when burrowing or crawling.

DISTRIBUTION/HABITAT

Pacific coast from Alaska to Baja California in the northern hemisphere and between Ecuador and Argentina in the southern hemisphere. E. analoga live in the swash zone (area of breaking waves) of the sandy beach intertidal zone.

DIET IN THE WILD

Antennae collect small organisms, mostly dinoflagellates which are brought to the mouth and consumed.

 REPRODUCTION

During the reproductive season (February-October), females can produce one clutch per month of 50-45,000 eggs, which take approximately 30 days to develop. Once the eggs hatch, the larvae are planktonic for 4-5 months.

PREDATORS

Fish, water birds, and shorebirds.

The barred surfperch is a very common fish in the surf zone, and sand crabs have been found to make up 90% of its diet.

Emerita analoga are  also used as bait by fishermen.

 

REMARKS

Sand crabs are known to carry parasites. They are an intermediate host of parasitic worms which are passed on to the predators of sand crabs. Sea otters and birds can eat many crabs per day, and the ingested parasites have been known to kill these predators.

Researchers monitor levels of DDT and domoic acid (a diatome neurotoxin) on a regular basis to assess the health of the ocean.

LOCATION Tidepool

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