Chelidonura hirundinina is seen sporadically on sandy lagoon reefs, often near patches of Halimeda algae. We have seen it from about 8 to around 30 meters on the sand slope of the Kwajalein eastern lagoon reef. Usually if you see one, you'll see a bunch. On 13 May 2007, large numbers were depositing eggs in a Halimeda patch in 6 to 8m on a Kwajalein east reef lagoon sand spit. The animals are somewhat variable in color. These were first reported in the Marshalls from Bikini Atoll as Chelidonura hirundinina elegans by Marcus (1965).
The two below are preparing to mate.
Always hard to resist shooting these colorful animals.
This one shows the fringe of sensory hairs on the anterior margin.
This is probably Chelidonura hirundinina, although we have never seen one with such an intricate pattern of orange. This was found at a depth of about 8m on sand in a Halimeda patch on the lagoon reef between Bigej and Meck Islands, Kwajalein Atoll, on 3 October 2016.
An especially dark form found in a Kwajalein reef quarry by Audrey Winkler.
The individual below was found at Ailinginae Atoll in the northern Marshalls by Ken Cone and Beth Van Zummeren.
The species is relatively common in Hawaii.
Created 27 January 2007
Updated 2 February 2022