120 — Mottled brittle star, Ophionereis fasciata

Mottled brittle star, Ophioneries fasciata,
Pilot Bay, Mt. Maunganui, July 2018.

Mottled brittle star, Ophionereis fasciata,
Pilot Bay, Mt. Maunganui, April 2018.

The same brittle star, curled up in a
?defensive ball, Pilot Bay, Mt. Maunganui,
July 2018.

Mottled brittle star, O. fasciata,
Pilot Bay, Mt. Maunganui, July 2018.

Mottled brittle star, O. fasciata,
Pilot Bay, Mt. Maunganui, July 2018.

Mottled brittle star, O. fasciata,
Pilot Bay, Mt. Maunganui, July 2018.

The mottled brittle star, Ophionereis fasciata *, is probably the New Zealand brittle star that people will mostly likely encounter. They are endemic to New Zealand and live under stones at low tide; but have also been found down in much deeper water (~300m).

An interesting thing about this brittle star is that it can produce bioluminescence in the form of blue flashes. It is thought that they use the bioluminescent flashes to ward off potential predators. Also, the chemical pathway for their bioluminescence is similar to that used by deep-sea lantern sharks (Claes et al., 2011).

Another possible defensive technique is shown on the left, where one has curled up into a tight ball with it's tube feet facing outwards. This brittle star reacted this way after encountering a crab.

However, these defensive techniques don't always work, as mottled brittle stars are eaten by a variety of fishes, particularly: red moki, porae, spectacled and variable triple-fins, and Sandagar's wrasse (Russell, 1983).

Now I know about the bioluminescence (I didn't before I researched this post), I'm going to plan a night expedition to see it...


* Hutton, 1872


































More info:

Claes, J. M., Krönström, J., Holmgren, S. & Mallefet, J. 2011. GABA inhibition of luminescence from lantern shark (Etmopterus spinax) photophores. Comp. Biochem. Physiol. C, 153, 231–236.

Mills et al. (2017). Extraordinary echinoderms. A guide to the echinoderms of New Zealand.

NIWA: Critter of the week.

Russell, B. C. (1983). The food and feeding habits of rocky reef fish of north-eastern New Zealand. The New Zealand Journal of Marine and Freshwater Research, 17, 121–145.