Ultramarine Magazine Issue 64 JuneJuly 2017

Hermit crabs aren’t just useful clean-up crew members, they are also fascinating to

watch and can really add to the diversity of a reef aquarium. A cursory glance how-

ever may not reveal the full extent of their day-to-day challenges, indeed new re-

search has recently shed light on the many ‘trials and tribulations of life as a hermit.

Researchers from found that crabs that had ‘fallen on hard times’ and were living in

damaged shells essentially became supercharged with aggression. Surprisingly, this

even allowed them to assault and evict much healthier and stronger crabs living in

more desirable undamaged shells.

This perhaps goes some way to explaining why hermit crabs can sometimes be

blamed for attacking other shelled organisms in a reef tank. In short, make sure

there are plenty of the right type and size of shell for your hermits if you want to

avoid them getting ‘crabby’!

Journal Reference: Guillermina Alcaraz, Gastón Ignacio Jofre. Aggressiveness compensates for low

muscle strength and metabolic disadvantages in shell fighting: an outcome of the individual’s past.

Behavioral Ecology and Sociobiology, 2017; 71 (6) DOI: 10.1007/s00265-017-2311-7

Image: J Clipperton

Did You

Know?