Dermasterias imbricata or the leather star is a starfish 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...

 Asteropseidae

Asteropseidae

Asteropseidae is a family of sea stars. Members of the family have relatively broad discs and five short tapering arms.-Genera:The following genera are listed in the World Register of Marine Species: *Asteropsis Müller & Troschel, 1840...

. It is found at depths of up to one hundred metres off the western seaboard of North America.

Description

The leather star has a broad central disc and five plump short arms which taper broadly from the central disc. The arms have two rows of tube feet and no bordering marginal plates. The upper surface is smooth and velvety, covered with a reticulated pattern in reddish-brown, often with patches of greyish-blue. There are no pedicellariae but the madreporite

Madreporite

The madreporite is a lightcolored calcerous opening used to filter water into the water vascular system of echinoderms. It acts like a pressure-equalizing valve. It is visible as a small red or yellow button-like structure, looking like a small wart, on the aboral surface of the central disk of a...

 can be seen. This starfish can grow to about twenty-five centimetres in diameter and has a distinctive smell that resembles garlic and sulphur.

Distribution

The range of the leather star includes the western seaboard of North America from central Alaska to northern Mexico. It lives in the littoral

Littoral

The littoral zone is that part of a sea, lake or river that is close to the shore. In coastal environments the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged. It always includes this intertidal zone and is often used to...

 zone and at depths of up to about one hundred metres.

Biology

The leather star feeds on algae

Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 and a range of invertebrates including other asteroid

Asteroid

Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

s, bryozoa

Bryozoa

The Bryozoa, also known as Ectoprocta or commonly as moss animals, are a phylum of aquatic invertebrate animals. Typically about long, they are filter feeders that sieve food particles out of the water using a retractable lophophore, a "crown" of tentacles lined with cilia...

ns, sea urchin

Sea urchin

Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...

s, sponges, sea cucumber

Sea cucumber

Sea cucumbers are echinoderms from the class Holothuroidea.They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. There are a number of holothurian species and genera, many of which are targeted...

s, hydroids

Hydrozoa

Hydrozoa are a taxonomic class of very small, predatory animals which can be solitary or colonial and which mostly live in saltwater. A few genera within this class live in freshwater...

, sea pen

Sea pen

Sea pens are colonial marine cnidarians belonging to the order Pennatulacea. There are 14 families within the order; they are thought to have a cosmopolitan distribution in tropical and temperate waters worldwide...

s and colonial tunicate

Tunicate

Tunicates, also known as urochordates, are members of the subphylum Tunicata, previously known as Urochordata, a group of underwater saclike filter feeders with incurrent and excurrent siphons that is classified within the phylum Chordata. While most tunicates live on the ocean floor, others such...

s.

In Washington state, spawning is from April to August. The females release yellow eggs which are fertilized in the water column. The larvae then become part of the zooplankton

Zooplankton

Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...

.

The leather star sometimes lives symbiotically

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 with the scaleworm Arctonoe vittata. The worm also associates with various other marine invertebrates but if separated from its host, will search out another member of the same species. The worm may nip off the heads of small tube-dwelling polychaetes as the starfish moves around but is not harmed by its host.

The parasitic barnacle Dendrogaster sp. is sometimes an endoparasite of the leather star.