Hiatella arctica
Encyclopedia
Hiatella arctica is a marine
bivalve mollusc in the family
Hiatellidae
, found in the Arctic Ocean
, and around all three main New Zealand
islands and the Chatham Islands
, plus Australia
's Macquarie Island
, from low water to depths of up to 180 m.
The thick shell is attached by thread-like hairs in holes, crevices or algal holdfasts, but often bores into soft rock and shells. The shell's shape is approximately oblong but highly irregular with no two specimens being alike. Two distinct ridges extend posteriorly from the beak on each valve. In juveniles, the ridges possess short spines that are often worn away in older specimens. The shell is sculptured
with thick concentric ridges.
This species is a suspension feeder. The type of substratum
selected by juveniles determines whether they become burrowers or nestlers. Those settling on hard rock will become nestlers while juveniles settling on soft rock become burrowers. The adults are able to bore into rock by mechanical abrasion using the valves of the shell. The initial penetration of the rock by juveniles may involve chemical as well as mechanical means.
Coloration is dull white with a coarse yellow-brown periostracum
, with a white interior.
Length is up to about 40 mm.
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
bivalve mollusc in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Hiatellidae
Hiatellidae
Hiatellidae is a family of bivalve molluscs in the order Myoida. It contains five genera.-Genera:* Cyrtodaria Reuss, 1801 * Hiatella Bosc, 1801** Hiatella arctica * Panomya Gray, 1857 * Panopea Menard, 1807...
, found in the Arctic Ocean
Arctic Ocean
The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions...
, and around all three main New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
islands and the Chatham Islands
Chatham Islands
The Chatham Islands are an archipelago and New Zealand territory in the Pacific Ocean consisting of about ten islands within a radius, the largest of which are Chatham Island and Pitt Island. Their name in the indigenous language, Moriori, means Misty Sun...
, plus Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
's Macquarie Island
Macquarie Island
Macquarie Island lies in the southwest corner of the Pacific Ocean, about half-way between New Zealand and Antarctica, at 54°30S, 158°57E. Politically, it has formed part of the Australian state of Tasmania since 1900 and became a Tasmanian State Reserve in 1978. In 1997 it became a world heritage...
, from low water to depths of up to 180 m.
The thick shell is attached by thread-like hairs in holes, crevices or algal holdfasts, but often bores into soft rock and shells. The shell's shape is approximately oblong but highly irregular with no two specimens being alike. Two distinct ridges extend posteriorly from the beak on each valve. In juveniles, the ridges possess short spines that are often worn away in older specimens. The shell is sculptured
Sculpture (mollusc)
The sculpture of a mollusc shell is the three-dimensional ornamentation on the outer surface, as distinct from the basic shape of the shell itself or colouration. Sculpture may be concave as well as convex. Sometimes it has microscopic detail. Sculpture refers to the calcareous outer layer, not the...
with thick concentric ridges.
This species is a suspension feeder. The type of substratum
Substrate (marine biology)
Stream substrate is the material that rests at the bottom of a stream. There are several classification guides. One is:*Mud – silt and clay.*Sand – Particles between 0.06 and 2 mm in diameter.*Granule – Between 2 and 4 mm in diameter....
selected by juveniles determines whether they become burrowers or nestlers. Those settling on hard rock will become nestlers while juveniles settling on soft rock become burrowers. The adults are able to bore into rock by mechanical abrasion using the valves of the shell. The initial penetration of the rock by juveniles may involve chemical as well as mechanical means.
Coloration is dull white with a coarse yellow-brown periostracum
Periostracum
The periostracum is a thin organic coating or "skin" which is the outermost layer of the shell of many shelled animals, including mollusks and brachiopods. Among mollusks it is primarily seen in snails and clams, i.e. in bivalves and gastropods, but it is also found in cephalopods such as the...
, with a white interior.
Length is up to about 40 mm.