50 million years of evolution have made cone snails one of the most successful marine animals. Let’s explore some of their unique adaptations.
The shape of the shell looks like a cone, hence the name cone snail. One predator of cone snails is crabs who use their claws to pry open snail shells. Their cone shape makes it hard for the crabs claws to grasp onto the shell long enough to pry it open. Most other animals without an exoskeleton would be stung by the cone snail in defense.
The shell shape is also designed to help the snail bury under the ocean floor. This protects the snail by keeping it hidden. A cone snail can eat prey that is as large as its body. If a cone snail has eaten a large meal, it may take a day or more to digest the entire meal. During this time, a cone snail would want to stay protected so it can remain stationary and safe while it eats. A cone snail would also find it useful to bury while it is attacking its prey. A nearby fish would not be alarmed by a thin proboscis or siphon, but it may if the entire shell was exposed.
You might think that the shell patterns are useful for the snail. This may be the case, but scientists aren’t sure why cone snails have such intricate and diverse patterns. The pattern has not been shown to correlate to toxin variation, hunting behavior, size, etc. In nature, some shells are covered with a slimy shell coat, called a periostracum, so their pattern isn’t even seen. The periostracum provides a camouflage for the cone snail in its habitat. Even without a currently known purpose, most would agree the patterns are extremely diverse and beautiful.
Chemicals may be secreted into the water by the cone snail to calm down or sedate their prey. This way the cone snail can get close enough to its prey to harpoon it. Most cone snails are nocturnal hunters so also feed when fish are sleeping.
Some net-hunters have finger-like projections that extend off the mouth. These may trick fish into thinking the mouth is an anemone or food such as worms. If they are also sedated, then the fish are swimming into a clever trick!