Sanddiver Escapes

Fish escape behavior is an ecologically extremely important behavioral pattern; many fishes are small animals, low in the food web, and a rapid and well-timed escape will make the difference between ending up as prey for a bigger fish or living on to thrive and eventually reproduce.

Sanddivers, Trichonotus sp., show an interesting type of escape behavior: they dive, as the name suggests, into the sand head first. I filmed them with a GoPro6 at 240fps, and slowed the footage down to 12% of its original speed. Note how the fish sometimes change direction just after initiating the escape, to make their position under the sand unpredictable:

How is this rapid movement initiated by the fish brain? This is rather well understood, and the key are a pair of neurons called “Mauthner” cells. The Mauthner cells are command neurons, they integrate information from several sensory systems and trigger an escape reflex. Here is a brief lecture on the Mauthner cells:

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