What’s on the van? – Harlequin shrimp

This week’s What’s on the van? comes from Sammy De Grave, assistant curator of the Museum’s Zoological Collection

Harlequin shrimps are monogamous, living in male-female pairs for life, sharing and actively defending a patch of reef of about 10 square meters. As you can see, they have exquisite colour patterns and a highly unusual morphology.

The main diet for the harlequin shrimp are starfish. Prey is located by either member of the pair, and even though the starfish may often be ten or twenty times larger than the shrimps, the harlequin shrimps flip over the starfish and drag them into their lair.

Once inside the lair, the starfish’s internal organs – tube feet and guts – are devoured, starting from the tips of the arms and working towards the central disk. This keeps the shrimps’ victim alive for as long as possible. It usually takes several days for the process to be completed. On occasion a starfish escapes, minus a leg or two, but usually they succumb.

A large scale program was initiated in the 1980s to attempt to harness this behaviour as a bioweapon against outbreaks of the Crown-of-Thorns starfish in the Pacific. However, due to their antagonistic territorial behaviour this was doomed because each pair of harlequin shrimps would kill all the others in close vicinity.

Sammy De Grave, Assistant Curator, Zoological Collection