Benthic fish are those that feed on the bottom (benthos). Most of them are slow and calm animals that spend their days grazing on algae, larvae of other fish, and small crustaceans.
The majority of these fish are territorial creatures, protective of the area they inhabit and careful about their own garden. Their territory provides them with food and shelter. If something affects the algae growing in their territory, they would have to migrate in search of new food, exposing themselves to their own predators. That’s why they dedicate a significant part of their day to clean their territory and keep their neighbors at bay.
Surgeonfish are particularly unique benthic fish. These beautiful fish rarely have their own specific area; you could say the entire reef is their territory. It’s common to see them in small schools of 20 or 30 individuals that launch a surprise attack on another fish’s territory, eagerly grazing and thinning out the algae in the targeted area.
Obviously, the homeowner doesn’t stay idle and tries to drive away the invading band. But the surgeonfish has a very distinctive defense mechanism. On each side of the base of its tail, it has a spine as sharp as a scalpel, which gives it its name. Normally, the spine is retracted and pressed against the body (in the photo, it’s shown in red), but when provoked, the spine takes a perpendicular position to the skin, resembling two dangerous knives. Interestingly, the spines are not hidden; on the contrary, it seems like the fish wants to highlight them, perhaps to discourage potential attackers.
With sideways tail swipes, the surgeonfish can inflict significant wounds on its assailant. The location of these spines allows the surgeonfish to repel the attack while continuing to feed. When the algae in the attacked area are depleted, it simply moves along the reef in search of another area to graze.
The laws of survival in the sea are often cruel and favor the best-equipped individuals. For every strategy, there is a defense mechanism. The adaptations of fish to their environment are numerous and diverse, resulting in an incredibly astonishing biodiversity. Raiders and those being raided cautiously navigate the intricate balance of life. Isn’t it always the case?
“You cannot defend what you do not love, and you cannot love what you do not know.”