Roger Steeb, USA
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Evasterias troschelii (Stimpson, 1862)
Evasterias troschelii is a species of starfish in the Asteriidae family. It occurs in Kamchatka and on the northwest coast of North America.
The description of this species was first officially published in 1862 by William Stimpson under the name Asterias troschelii (Stimpson first introduced the new species in an 1861 lecture to the Boston Society of Natural History). The holotype was collected in Puget Sound, Washington. Only part of an arm remains of this smaller specimen in the United States National Museum.
Evasterias troschelii is a large starfish with a radius of up to 28 centimeters. It has a small disc and five long, narrow arms, often pointing upwards at the tip. The widest point of the arms is slightly from the edge of the disk. The surface is covered with a network of calcareous plates with spines about 2 mm long surrounded by smaller spines and crossed and straight pedicellaria.
Down the center of the arms is an irregular line of white-tipped spikes. The entire top feels rough. On the surface, a long ambulacral groove extends from the central mouth to the tip of each arm, with four rows of tube feet and assemblages of pedicellaria and spines on either side.
The color is very variable and includes plain or mottled shades of orange, brown, grey-green, blue-grey and light purple. The outer edges of the arms often have a contrasting colored border and the underside is tan.
It is mostly found on rocks and stones, occasionally on sand.
In the north of its range, spawning occurs from April to June. Many small eggs are produced. Fertilization occurs externally. The larvae that develop from this are part of the zooplankton and spread with the currents.
The spotted starfish is a predatory species. It feeds mainly on mussels. With its tubular feet, it can exert a strong pull on the two flaps of a mussel shell and pull them apart far enough that it can insert part of its stomach through the gap. It then uses digestive enzymes to break down the mollusc's tissues before sucking it out and separating its stomach from the shell. It also eats barnacles, chitons, snail molluscs, tunicates and brachiopods. Some limpet species show behavioral responses to the presence of the speckled star and are able to evade it.
The scaleworm Arctonoe fragilis often lives on the surface or in an ambulacral groove of the starfish as a commensal. The ciliated parasite Orchitophrya stellarum has multiple hosts, including Evasterias troschelii. It lives between the spines on the body and arms until the starfish is ready to reproduce and then moves into its host, likely through a gonopore. It gets to the gonads of the male starfish and feeds on the sperm, effectively castrating its host.
Juvenile Alaskan king crabs (Paralithodes camtschaticus) have been observed living as commensals on the surface of Evasterias troschelii and sheltering between its arms.
Predators of the starfish include adult king crabs, intertidal gulls, as well as the sun starfish (Solaster dawsoni) and sunflower starfish (Pycnopodia helianthoides).
Synonymised names:
Asterias acanthostoma Verrill, 1909 · unaccepted (Synonym)
Asterias brachiata Perrier, 1875 · unaccepted (Synonym according to Verrill...)
Asterias epichlora Brandt, 1835 · unaccepted
Asterias saanichensis deLoriol, 1897 · unaccepted (synonym according to A.M. Clark &...)
Asterias troschelii Stimpson, 1862 · unaccepted
Asterias victoriana Verrill, 1909 · unaccepted (Synonym according to Djakonov (1950))
Evasterias acanthostoma (Verrill, 1909) · unaccepted
Evasterias alveolata Verrill, 1914 · unaccepted
Evasterias troschelii var. alveolata Verrill, 1914 · unaccepted
Leptasterias epichlora (Brandt, 1835) · unaccepted
Leptasterias inaequalis Verrill, 1914 · unaccepted (Synonym according to Fisher (1930))
Leptasterias macouni Verrill, 1914 · unaccepted (Synonym according to Fisher (1923))
Direct children (5):
[Forma Evasterias troschelii f. parvispina Verrill, 1914
Variety Evasterias troschelii var. densa Verrill, 1914
Variety Evasterias troschelii var. rudis Verrill, 1914
Variety Evasterias troschelii var. subnodosa Verrill, 1914
Variety Evasterias troschelii var. alveolata Verrill, 1914 accepted as Evasterias troschelii (Stimpson, 1862)
Evasterias troschelii is a species of starfish in the Asteriidae family. It occurs in Kamchatka and on the northwest coast of North America.
The description of this species was first officially published in 1862 by William Stimpson under the name Asterias troschelii (Stimpson first introduced the new species in an 1861 lecture to the Boston Society of Natural History). The holotype was collected in Puget Sound, Washington. Only part of an arm remains of this smaller specimen in the United States National Museum.
Evasterias troschelii is a large starfish with a radius of up to 28 centimeters. It has a small disc and five long, narrow arms, often pointing upwards at the tip. The widest point of the arms is slightly from the edge of the disk. The surface is covered with a network of calcareous plates with spines about 2 mm long surrounded by smaller spines and crossed and straight pedicellaria.
Down the center of the arms is an irregular line of white-tipped spikes. The entire top feels rough. On the surface, a long ambulacral groove extends from the central mouth to the tip of each arm, with four rows of tube feet and assemblages of pedicellaria and spines on either side.
The color is very variable and includes plain or mottled shades of orange, brown, grey-green, blue-grey and light purple. The outer edges of the arms often have a contrasting colored border and the underside is tan.
It is mostly found on rocks and stones, occasionally on sand.
In the north of its range, spawning occurs from April to June. Many small eggs are produced. Fertilization occurs externally. The larvae that develop from this are part of the zooplankton and spread with the currents.
The spotted starfish is a predatory species. It feeds mainly on mussels. With its tubular feet, it can exert a strong pull on the two flaps of a mussel shell and pull them apart far enough that it can insert part of its stomach through the gap. It then uses digestive enzymes to break down the mollusc's tissues before sucking it out and separating its stomach from the shell. It also eats barnacles, chitons, snail molluscs, tunicates and brachiopods. Some limpet species show behavioral responses to the presence of the speckled star and are able to evade it.
The scaleworm Arctonoe fragilis often lives on the surface or in an ambulacral groove of the starfish as a commensal. The ciliated parasite Orchitophrya stellarum has multiple hosts, including Evasterias troschelii. It lives between the spines on the body and arms until the starfish is ready to reproduce and then moves into its host, likely through a gonopore. It gets to the gonads of the male starfish and feeds on the sperm, effectively castrating its host.
Juvenile Alaskan king crabs (Paralithodes camtschaticus) have been observed living as commensals on the surface of Evasterias troschelii and sheltering between its arms.
Predators of the starfish include adult king crabs, intertidal gulls, as well as the sun starfish (Solaster dawsoni) and sunflower starfish (Pycnopodia helianthoides).
Synonymised names:
Asterias acanthostoma Verrill, 1909 · unaccepted (Synonym)
Asterias brachiata Perrier, 1875 · unaccepted (Synonym according to Verrill...)
Asterias epichlora Brandt, 1835 · unaccepted
Asterias saanichensis deLoriol, 1897 · unaccepted (synonym according to A.M. Clark &...)
Asterias troschelii Stimpson, 1862 · unaccepted
Asterias victoriana Verrill, 1909 · unaccepted (Synonym according to Djakonov (1950))
Evasterias acanthostoma (Verrill, 1909) · unaccepted
Evasterias alveolata Verrill, 1914 · unaccepted
Evasterias troschelii var. alveolata Verrill, 1914 · unaccepted
Leptasterias epichlora (Brandt, 1835) · unaccepted
Leptasterias inaequalis Verrill, 1914 · unaccepted (Synonym according to Fisher (1930))
Leptasterias macouni Verrill, 1914 · unaccepted (Synonym according to Fisher (1923))
Direct children (5):
[Forma Evasterias troschelii f. parvispina Verrill, 1914
Variety Evasterias troschelii var. densa Verrill, 1914
Variety Evasterias troschelii var. rudis Verrill, 1914
Variety Evasterias troschelii var. subnodosa Verrill, 1914
Variety Evasterias troschelii var. alveolata Verrill, 1914 accepted as Evasterias troschelii (Stimpson, 1862)
