Some species of Filefish are known to wedge themselves into corals at night and it is theorized that the corals assist in masking their smell from predators. However as can be seen in the images not only do they wedge themselves into the corals, they often bite onto the corals and sponges to hold themselves in place.
In the Red Sea they have been previously recorded as biting onto coral to anchor themselves and the behavior was named teeth anchoring. As can be seen in the images we commonly see this behavior at night among several species of Filefish in Tanzania. The specimen above however is the first we have seen anchored on a sponge.
Similar behavior among Filefish has been documented in the Gulf of Mexico and juvenile pelagic Filefish have been documented biting onto Jellyfish and floating coral polyps.
Apart from anchoring themselves onto the corals the often wedge themselves in the coral as well, raising the dorsal fin to assist in wedging themselves in. On some occasions they both wedge themselves in and bite onto the coral.
This behavior seems quite common and in the images there are four different species using the behavior. They are additionally often seen pressed sideways onto sponges.
This anchoring behavior has also been noted among minnows in North America when they are subjected to strong currents.
What is interesting is that they often both wedge themselves into the coral , which would be sufficient to hold them in place, yet they simultaneously bite onto the corals as well.
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