FLAME BOX crab being stalked

Box crabs (Calappidae) mainly hunt by digging in the sand and rubble to find marine mollusks which they can then crack open with their powerful claw. In Bonaire, you can typically see a Flame Box crab (Calappa flammea) walking around in the shallow sand. If they are threatened, they can easily dig themselves into the sand and burrow there with only their little eyes protruding until the threat is gone.

While the crab goes about its business walking around and digging in the sand, it attracts some followers that would like to benefit from this behavior. In several instances, I have observed this situation: A wrasse or a flounder will follow the crab hoping to benefit from the hunting that it does so that as the little bits and pieces of mollusks that the crab digs up surface, the fish can also get their share of the action and have a free meal.

There was no indication that the crab was bothered by its stalkers or any indication that the fish tried to grab the crab’s food. The wrasse was a bit more intrusive in its stalking behavior which seemed to halt the crab a bit though.

These observations I had along with the videos I have shot lead to a co-authored paper with Werner de Grier that was published in The Ecological Society of America in April 2020. You can read it here: https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecy.3068

Below are the 2 videos that show the behavior:

1) One where the crab is being followed by a Slippery Dick wrasse (Halichoeres bivitattus)

2) Another by a Maculated Flounder (Bothus maculiferus).