Red-legged hermit crab
6Scientific name: Paguristes cadenati
6Origin: Across the Caribbean
6Size: Leg span around 4cm max
6Feeding: Offer meaty foods like brine shrimp and Mysis, and allow some algae to grow in the tank 6Availability and price: Very common, prices from around £5 upwards
among the hermits, and they’re on the naughty list for more than one reason. Don’t get me wrong - they are stunning animals and are indeed quite charismatic, but such charm belies their more destructive tendencies. These brutes are by no means superpredators, but anything that is slow enough to find itself between a large hermit’s claws will be food forevermore; this includes sleeping fishes and shrimps. Corals and other invertebrates, too, will slowly but surely make their way onto the menu.
In a display with bigger, situationally-aware fish these crabs aren’t half bad. On the contrary, saddling them up with anything small or slow will be disastrous.
Finding appropriate shells to house them in can be problematic at best. Fully grown crabs need shells around the size you’d see from large Turbo snails, conches and the like, which you might have luck sourcing from your nearest shoreline, or a tragically talentless snail keeper. A range of other shell sizes are becoming readily available from various online vendors (eBay is packed with decorative shell sellers, but the prices somehow remain high), usually but not always intended for land hermits.
Being able to differentiate these beasts from the rest is important, especially since they’re imported at fairly small sizes.
If they are sold with names, look out for these: Red hairy hermit, Dardanus megistos, the Hairy hermit, Aniculus maximus, and the Giant
hermit, Petrochirus diogenes.
The first two are quite bristly, while the last offender is pinkish with a knobbly texture to its surface. Other species in these genera may be similarly-sized, and in many cases share similar temperaments.
These animals will need to be fed with offerings of the meaty sort, and never too large. Rather, feed smaller amounts more regularly than risk a stray piece of prawn drifting under some live rock and rotting. They’re usually quick to find food but missed morsels are just a problem waiting to happen.
Perhaps the only silver lining offered by these larger, polyp-crazed decapods is that they occasionally take a liking to eating Aiptasia, although whether this is opportunistic or preference is not yet a clear-cut story.
My closing advice is to do as all good aquarists do: observe. Even the angelic, ‘reef-safes’ hang their halos on a pair of horns, so you need to monitor the dynamics these animals will have with the rest of your living system.
Most trouble, if any, can be caught early on, and hopefully be mitigated or resolved before your hermits raise too much (s)hell.