How Do Sea Stars Defend Themselves?

Sea stars, also known as starfish, are fascinating creatures that are unlike anything else on earth. These marine animals dwell deep in the ocean waters; they are, quite literally, star-shaped, with anywhere from five to forty arms depending on which species they are (and there are over 2,000 species of sea stars on earth). Their instantly-identifiable shape and unique characteristics, such as their ability to regenerate if one of their limbs is severed, make them a favorite among everyone from children to marine biologists. They’re well known to most people, and a subject of overwhelming interest.

Sea stars defend themselves in a number of different ways. Most of the ways that sea stars defend themselves is through the use of various natural defenses such as:

• Spines and shells
• Camouflage
• Detachable Limbs

One of the most intriguing things about sea stars is the various natural methods of defense they have, which help defend them against would-be predators.

Spines and Shells

If you’ve ever handled a sea star, you probably know that the majority of them have a smooth underside, with a round mouth directly in the center. This part of the body is vulnerable, which is why it is, in fact, the “underside” of the sea star: it spends most of its time against the ocean floor, where it’s protected. The rest of the body, on the other hand, is a different story.

The back of a sea star is generally much harder than the belly, forming what is almost a shell of protection; when the sea star lies flat with its back on top, it can be nearly impenetrable.

Some sea stars have smooth backs, but many others have sharp spines that contribute even more to their defense. What’s more, nearly all species have rows of spines, some almost invisible to the eye, which run along each one of their arms. Any predator who attempts to grab a sea star by its convenient protrusions is in for a nasty surprise.

Camouflage

There are a few more unique defense methods among sea star varieties, some more common than others, but all fascinating in their own ways. For example, some species of sea stars are camouflaged, often in strange muddy green and brown blotches that blend into algae and mud on the ocean floor. This allows them to lie still and become, to some extent, invisible to predators.

Speaking of invisibility, many of them also take advantage of the simple tactic of hiding. Sea stars are excellent at squeezing themselves between rocks and behind ledges, or even burrowing into the ocean floor itself, in order to conceal themselves.

Detachable Limbs

Perhaps their most famous defense of all is limited to just a few varieties of sea stars, but does in fact really happen: should a predator grab the sea star by one of its arms, the arm will literally snap off of the body, allowing the sea star to escape. These “brittle” species of sea star are the ones who take the most advantage of the ability to regenerate limbs!

Know Where to Look for Defense

All animals in nature have some form of defense that’s part of their natural development, and sea stars are no exception to the rule. The defenses available to sea stars, though, are perhaps more intriguing than most, and are also more difficult to identify unless you know where to look.