Brisingidae

Lore & Background

Members of this family have a small, Ophiurida-like disc, clearly demarcated from the arms, which number more than five. The disc is approximately circular with a rim of fused plates which gives rigidity. The madreporite is near the margin of the disc. The arms are long and tapering with the ratio of the arm length to the disc radius being greater than 6/1. There is an acute angle between them and they can be shed at the base where they are separated from the disc by a deep groove. After a narrow cylindrical portion, the part of the arms closest to the disc accommodates the gonadal tissues and widens out somewhat. Beyond this area, the arms taper to a long point. The plates on the aboral (upper) side of the arms are small, and are much smaller than the marginal plates, which are armed with spines. The ambulacral groove on the underside of each arm is broad and there is a row of tube feet with suckers on either side of the groove. The pedicellariae are crossed.

Members of this family live on hard surfaces at depths between 100 and 4,500 m (300 and 14,800 ft). They raise their arms vertically above their discs to filter feed on suspended organic particles drifting past. They are able to raise their arms in this way because of the small size of its plates on the aboral surfaces of their arms which gives them flexibility in a vertical plane. Novodinia is less adept at raising its arms, because of a different arrangement of the plates; in contrast, members of the other brisingid family, Freyellidae, have not been detected raising their arms in this way.

Reader's Guide

The Brisingidae are notable as a family of starfish restricted to deep-sea environments, occurring across major ocean basins including the Atlantic, Pacific, Southern Ocean, and around Antarctica. Their name derives from Brísingamen, a necklace from Norse mythology stolen by Loki and hidden in the sea, linking their discovery to a mythological narrative. Their physical characteristics—a small disc, more than five long arms, and the ability to shed arms at the base—distinguish them from other starfish. The family's feeding behavior is unique: they raise their arms vertically to filter feed on suspended organic particles, a posture enabled by the small size of the aboral arm plates. This ability is not shared equally among related groups; Novodinia is less adept due to a different plate arrangement, and Freyellidae have not been observed raising their arms at all. The family's biology and morphology, as described, highlight adaptations to deep-sea life on hard substrates, with tube feet and crossed pedicellariae contributing to their ecological role.

Did You Know?

• The family Brisingidae is named after Brísingamen, a necklace belonging to Freya from Norse mythology.
• Members of this family have more than five arms, with an arm length to disc radius ratio greater than 6/1.