Sunday, May 1, 2011

The King Crab


by Noni Heers


Kingdom: Animalia

Phylum: Arthropoda

Subphylum: Crustacea

Class: Malacostraca

Order: Decapoda

Infraorder: Anomura

Superfamily: Lithodoidea

Family: Lithodidae

I. Introduction

King Crabs are a superfamily of crustaceans mainly found in cold waters. Because of their large size and the taste of their meat, many species are widely caught and sold as food, the most common is the red king crab.

II. Anatomy


The anatomy of King crab consists of shoulders, merus, legs, claws, joints, tips, spines and a carapace. King crabs molt their shell in order to get bigger. Juvenile king crabs molt frequently the first years of life and molt less when they reach 4-5 years of age. Alaskan king crab are known by their exterior color. Red king crab has a dark reddish brown shell, blue king crab has a blue tone shell and golden king crab has a dark brown shell. Blue king crab legs are slender and more oval shaped compared to red king crab legs. King crab is measured by the number of king crab legs it takes to reach 10 pounds of crab meat.

III. Form and Function

The cuticle that covers the body and limbs of the king crab is divided into segments interconnected by strong, flexible membranes, allowing movement at the joints. The cuticle is highly mineralized or impregnated with calcium salts. Such an exoskeleton provides considerable mechanical leverage and protection to the crab.

Their central nervous system consists of a central nervous system, a ventral nerve cord and ganglia within each body segment. They also have eyes, antennules, and antennae, and mouth parts in the head region.

Feeding and Digestion

The mouth opens on the bottom of the Crab. All of these appendages are thought to be primarily manipulative and food-handling, even though one of them seems also to function to pump water across the gills. There are large mashing jaws located on either side of the mouth and they smash food pretty well, but most of the chewing is done in the stomach. Because of crabs hard exoskeleton, the mouth can't open very wide, Instead, they are "tearing" predators or scavengers which use their large claws to tear off pieces of the food item. These pieces are passed to the maxillipeds covering the mouth and they rip it into progressively smaller pieces. Eventually, the food item is shoved between the jaws and into the small mouth. Food at this stage is a pulpy mass.


When a male and female crab mate, many female decapod crabs can store the male sperm until her eggs are ready to be released. When the eggs are released, the stored sperm flows over them and they become fertilized. The female crab holds the fertilized eggs in a big spongy mass between its abdominal flap and the body. The eggs are cemented to the pleopods, which are small legs, creating the "berried" appearance. To keep the eggs healthy, the female crab continually "waves" water over the eggs with the pleopods. When the eggs hatch into zoea larvae, they drift away in the ocean currents as plankton.

IV. Impact on the World and Humanity

The biggest impact that KIng Crabs have, are their delicious legs. A lot of people like eating some tasty crab legs especially HUGE ones :)


V. Journal Article and Review

In the article that I read it talked about how thousands of King Crabs were coming up the Antarctic slope. James McClintock said "They are coming from the deep, somewhere between 6,000 to 9,000 feet down," If the species continue to show up on shore we could lose the disease fighting compounds.

Works Cited

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