The dorsal fin (the one on its back) of a bass is an active defence against predators bigger than itself, such as diving birds like cormorants when the fish are quite small. The fin is supported by a row of very sharp spines. If something tries to swallow it the fish erects – pushes up – these spines so that they stick in the creature’s throat. Some bass may die, but other creatures learn to leave them alone.
The gill covers of a bass are very sharp, like a pair of razors either side of its head. If it is attacked it will push them out and shake its head, so that the side to side movement can do a great deal of damage to its enemy. This is probably why they shake their heads when they are caught on an angler’s line. They can’t see the threat but they respond to it in an instinctive manner.
Colouration
Bass do a lot of their hunting at night or in water which is relatively deep. As a result their backs are somewhat darker than the rest of their bodies. If you are wondering why then you need to think about ways in which the bass can ambush its prey. The darker back makes them harder to spot in an upward lunge, but it also makes them harder for predators to spot when they are fleeing quickly for cover on the ocean floor. The silvery undersides also make them harder to spot from below, just as in the case of the mackerel.
The powerful tail and build of the bass are both indicators of its predatory nature. It is not designed for sustained high speed, unlike the mackerel which can, over distance, leave the bass standing, but rather for very short bursts of sudden acceleration. This is why it likes to have a hiding place from which it can emerge in a devastating strike and then return safely to cover.
The mouth of the bass is the final giveaway to its predatory nature. It is very large for the size of the fish, which means that the bass can swallow a very large meal in one easy gulp. This is a much more efficient way of gathering food than chasing after lots of small meals. It makes much better use of the energy from everything eaten.
