Rossia pacifica

Geographic Range

Northern Atlantic Ocean and the Pacific Ocean.


These animals are swim freely in the marine environment. Inhabit shallow reef areas, sand and rubble bottoms to depths of more than 5000m.

Physical Description

These animals have a large body cavity, a closed circulatory system, a complex brain, a highly responsive nervous system, and head with large & complex eyes. They are small; maximum length (excluding tentacles) is 10 cm. Their bodies are short and rounded at the posterior end. They have 8 short arms (each with 2-4 ros of suckers) and 2 long arms, which can be almost entirely withdrawn into the body. The shell, or "pen," is internal, slender, and very thin and delicate. These squid also have large, semi-circular fins on the middle of the sides of the body.


The sexes are separate. Males impregnate the females with a modified arm tip that transfers sperm. The male grasps the female from the ventral side with the long tentacles. Animals are oriented so that both heads face the same direction. Male's hectocotylus, its left first arm, is inserted into the female's mantle cavity, where it deposits the spermatophores.


When in danger: crawls rapidly to the bottom, head supported by the arms, by pulling itself along by the arms, which are extended in all directions. Excavates by blowing water. Capable of expelling an inky cloud to confuse predators.

Food Habits

Highly adapted for raptorial feeding and a carnivorous diet. Locate prey with their highly developed eyes, capture it with the appendages.


Alejandra Montes (author), University of Michigan-Ann Arbor.


Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


the nearshore aquatic habitats near a coast, or shoreline.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

native range

the area in which the animal is naturally found, the region in which it is endemic.


structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.


Robert D. Barnes, "Invertebrate Zoology 5th ed." (Fort Worth: Saunders College

Publishing, 1987) 207. <BR>

Richard C. Brusca and Gary J. Brusca, "Invertebrates" (Massachusetts: Sinauer Associates Inc., 1990) 709. <BR>

J. David George and Jennifer J. George, "Marine Life" (New York: Wiley-Interscience Publication, 1979) 333. <BR>

Neville Coleman, "Encyclopedia of Marine Animals" (London: Cassell Imprint, 1991), 113. <BR>

Alfred Kaestner, "Invertebrate Zoology" (New York: Interscience Publishers, 1967) 410, 411, 414, 419. <BR>

Abbot, R. T. 1954. American Seashells. D. Van Nostrand Co., Inc.