Northern basket star

Gorgonocephalus arcticus

ORDER Euryalida

FAMILY

Gorgonocephalidae TAXONOMY

Gorgonocephalus arcticus Leach, 1819. OTHER COMMON NAMES

German: Gorgonenhaupt; Norwegian: Medusahode. PHYSICAL CHARACTERISTICS

A large basket star with a disk 4.01 in (102 mm) in diameter, with highly branched long (14.1 in or 360 mm) arms. The disk is pentagonal and bare, leathery with five pairs of ridges radiating from the center to the sides of the arms. The five sturdy arms divide into two branches near the disk and then redivide equally five or more times. The arm joints have short hooked spines. Color varies from yellowish brown to darker brown with lighter arms.

DISTRIBUTION

North Atlantic, from the arctic region to Cape Cod in the northeastern United States.

HABITAT

On rocky bottoms swept by currents, often clinging to gor-gonians at a depth of 164-4,921 ft (5-1,500 m).

BEHAVIOR

Northern basket stars are adapted to live in strong ocean currents and seek out positions high up in the water column in order to spread out their feeding fans in the form of a concave dish facing the current. They can hold out their arms in a stiff position for long periods of time. There is morphological evidence that the mutable collagenous tissues (MCT) of basket stars may be important in maintaining their stiff fans. The use of MCT lowers the rate of energy consumption in comparison to using muscles for the same purpose. In contrast to shallow-water basket stars that are strictly nocturnal, Gorgonocephalus arcticus uses its feeding fan during the day.

FEEDING ECOLOGY AND DIET

Gorgonocephalus arcticus is a predatory suspension feeder that captures zooplankton, primarily such macroscopic crustaceans as krill, by rapidly coiling and bending its arms. Rings of sharp

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