Calliaster kyros
A spiny sea star from deep waters off New Caledonia.
Calliaster kyros, a sea star belonging to the family Goniasteridae, lives in the waters off New Caledonia. Its species name, *kyros*, comes from the Greek word for "lord" or "master."
This species closely resembles *Calliaster hystrix*, as both have many bivalved pedicellariae on their actinal (underside) surface. However, *C. kyros* stands apart due to the very striking spines on its abactinal (upper) and marginal plates, and because its superomarginal plates are abutted (touching) along the arm, with more than half of the distal paired plates also meeting.
The body is star-shaped, with five triangular, long, tapering arms ending in pointed tips. On the upper surface, distinct, conical, pointed spines appear on the primary circlet and along the central series, with more variable spines in the interradial areas. The superomarginal plates are abutted over the midline, numbering 10 to 15 along each arm; abactinal plates are limited to the disk and a triangular area on the arm before the abutted superomarginal plates begin. These superomarginal plates have two series of spines: one on plates touching the disk, pointing upward, and another extending along most of the arm, pointing sideways. The underside, especially near the adambulacral series and about half of the actinal intermediate plates, features large bivalve pedicellariae with large, round valves that have rough to toothed edges. There are 8 or 9 furrow spines, and 2 to 4 large, thick subambulacral spines.
This sea star is known only from off New Caledonia, at depths between 274 and 460 meters.
Quick Facts
- Genus
- Calliaster
- Species
- kyros
Facts from the source article.
Lore & Background
The species epithet kyros is derived from the Greek for 'lord' or 'master.' In taxonomy and systematics, Calliaster kyros is similar to Calliaster hystrix in sharing numerous bivalved pedicellariae on the actinal surface. However, C. kyros is distinguished by the very striking armament present on the abactinal and marginal plates as well as by having abutted superomarginal plates that include over half of the distal paired plates along the arm.
The species has a stellate body with five triangular, elongate, tapering arms with pointed tips. The abactinal surface has distinct, conical, pointed spines on the primary circlet and along the carinal series, and more variably in interradial regions. Superomarginal plates are abutted over the midline, with 10–15 along the arm; abactinal plates are present only on the disk and a triangular region onto the arm prior to the abutted superomarginal plates. Superomarginal plates have two spine series, one series present only on plates in contact with the disk and directed dorsally, and a second series extending along most of the arm and directed laterally. The actinal surface, especially adjacent to the adambulacral series and approximately 50% of actinal intermediate plates, has large bivalve pedicellariae with large round valves bearing rough to teethed edges. Furrow spines number 8 or 9. Subambulacral spines number 2 to 4 and are large and thick.
Reader's Guide
Calliaster kyros is significant as a deep-sea species of the family Goniasteridae, documented only from off New Caledonia at depths of 274 to 460 meters. Its description highlights a striking armament on the abactinal and marginal plates, which distinguishes it from the similar Calliaster hystrix. The species' etymology, meaning 'lord' or 'master,' adds a cultural note to its scientific identity. The detailed morphology—including five triangular arms, conical spines, abutted superomarginal plates, and large bivalve pedicellariae with rough-edged valves—provides a clear basis for identification. The presence of 8 or 9 furrow spines and 2 to 4 large, thick subambulacral spines further characterizes this starfish. Its legacy lies in contributing to the understanding of goniasterid diversity in the southwest Pacific, with no further information on its ecology or conservation status available from the source.
Frequently Asked Questions
What is Calliaster kyros?
Calliaster kyros is a spiny, five-armed sea star in the family Goniasteridae that inhabits deep waters off New Caledonia, typically between 274 and 460 meters. Its species epithet, kyros, is drawn from the Greek word meaning 'lord' or 'master.'
Where can you find Calliaster kyros in the wild?
This species is known from the deep-sea environment surrounding New Caledonia, where it lives at depths ranging from roughly 274 to 460 meters. It is a benthic organism, meaning it rests on or near the ocean floor in that zone.
How is Calliaster kyros different from the similar Calliaster hystrix?
While both species share numerous bivalved pedicellariae on their undersides, C. kyros is set apart by its notably bold spines on the upper and marginal plates. Additionally, its superomarginal plates press directly against one another along the arm, and more than half of the distal paired plates also meet, a feature C. hystrix lacks.
What does Calliaster kyros look like?
It has a classic star-shaped body with five arms, covered in prominent spines on the abactinal and marginal plates. The underside carries eight or nine furrow spines and two to four subambulacral spines, giving it a heavily armored appearance.
Why is Calliaster kyros notable among deep-sea starfish?
Its combination of striking upper-surface spination and the distinctive abutting pattern of its marginal plates makes it a useful reference point for separating it from look-alike species in the Goniasteridae. It also represents one of the deeper-dwelling members of the genus Calliaster, found well below 250 meters off New Caledonia.
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