In a Squid What Are Its Fins For?

Purpose of Fins

• Squid fins serve two basic purposes for the animals. These purposes are locomotion and control. Locomotion entails movement from one place to another. Thus squids use their fins to travel through water, as a means of propulsion. The fins also serve a similar purpose to rudders, helping squids control the direction in which they travel. The use of fins as rudders holds special prominence when squids move backwards, since the fins sit at the back of a squid's body, and thus the front when squids move backward. In cases of backward movement, fins work like front wheel drive.

Use of Fins

• Squids use fins in conjunction with various other parts of the mantle to optimize locomotion, directional control and speed. Squids possess jets that sit very close to its fins on the animal's mantle. Squids use jets to rapidly and forcefully expel water. This expulsion generates force that moves squids through water. When squids move at a normal pace, they use their fins in conjunction with the jets to create forward or backward movement and directional control. When squids move in very quick bursts, they pull their fins close to their mantles to create a more hydrodynamic form.

Fins in Relation to Species

• The prominence of fins in the movement of a squid depends on the species. Richard Ellis, author of "Monsters of the Sea," writes that some species of squid, such as those of the Dosidicus genus, possess large, powerful fins that figure prominently into the locomotion of the animals. Squids of the Architeuthis genus, or giant squids, on the other hand, possess proportionally small fins, meaning that other factors, such as propulsion created by jets and muscles in other parts of the squid, figure more prominently in locomotion.

More Info on Squid Fins

• The shapes of fins vary depending on the species of squid. According to a paper by JA Hoar, et al. published in the book "Mechanics and Physiology of Animal Swimming," on the role of fins in competition between fish and squids, the shape of a squid's fins likely holds an evolutionary purpose. Understanding the purpose of fin shape helps scientists understand the habits of squids rarely seen by humans.

  Squid fins contain the same type of muscle tissue and elastic connective tissue found in the fins of fish. Many squid species use fins in the same manner that fish use their fins to swim. Both fish and squids use their fins in conjunction with a dual muscle system that employs one set of muscles for fast motion and one set for slow motion.