Starfish are some of the most recognized undersea creatures due to their characteristic shape, which is universally known as a star. They seem such gentle, sedentary creatures, but starfish are pretty fascinating in their lifestyle. There are hundreds of species of starfish, displaying many colors and shapes, and they can have more than five arms. Let’s take a look at some facts about starfish and the life they live.
Starfish is Not a Fish!
That’s right, we named something a fish that is not a fish. Starfish are, in fact, echinoderms, which also include sea cucumbers, urchins, and sand dollars. They have what is known as a mesodermal skeleton, which is a system of calcium carbonate plates held together by the animal’s tissues. The starfish’s skin is bumpy, spiny, and, in some cases, venomous. The underside of the starfish is covered in nodules known as tube feet. These are what the starfish uses for transportation and opening mollusks. Starfish have microscopic eyes on the end of each arm. Although we call it a fish, there are vast differences between the invertebrate echinoderm and a vertebrate!
Starfish Can Regenerate Limbs
One of the starfish’s most incredible feats is its ability to detach its limbs when faced with danger. Starfish are a bilaterian creature and begin life as a free-swimming ciliated organism, meaning a cell body with a protuberance. As the starfish develops, one side of the starfish grows to full size, at which time the other half will grow symmetrically to full size, resulting in a symmetric 5-sided star shape arranged around the central axis of the mouth. If a starfish should decide to shed an appendage, the creature’s biological processes involve stem cells regenerating tissue and, eventually, an entire limb. At the same time, it is not typical for a detached appendage to regenerate an entirely new body, but a few species have been recorded as capable of doing so.
Harlequin Shrimp is a Natural Predator
This fact is fascinating because harlequin shrimp only grow to be a maximum of 2 inches long! The size of a starfish is irrelevant to the harlequin shrimp; however, if it is on the prowl for starfish. Rarely will harlequin shrimp feed on sea urchins, but starfish is its primary food source. Despite the starfish being several times larger, the harlequin shrimp have an efficient method of trapping and consuming starfish, usually working in pairs. The team will flip the starfish over after clipping its tube feet to release it from the rock or coral it’s attached to and then drag it back to their home, where it is consumed alive. Some harlequins have even been observed feeding the captured starfish to keep it alive and fresh for their feast. Starfish also have other, more apparent predators: sharks, crabs, sea birds, and enormous starfish.
Starfish are Ecologically Important
Because the starfish’s diet mainly consists of shellfish, they play an essential role in regulating shellfish populations that would otherwise proliferate an area, making the ecosystem’s balance disproportionate. If mollusks reproduce unfettered, seaweed and other plants are denied surface area to grow, reducing a food source for many species that rely on the plants for survival. Starfish are part of a group known as keystone species, meaning they play a vital role in keeping the ecosystem thriving. The one exception to this statement is the crown-of-thorns starfish, which destroys reef ecosystems by preying on the coral that comprises the reefs.
The life of a Starfish is a fantastic creature to behold and explore. When was the last time you saw or touched one?
