Have you ever picked up a little pentagonal object on the beach? Have you ever seen a herd of colorful critters in an aquarium? Have you ever wondered what these little things are? And how do they live? Today, I am going to take you into a wonderful and beautiful world - the world of starfish.
Starfish are not "stars" in the true sense, nor are they "fish" in the true sense. They are an echinoderm and belong to the same phylum as sea urchins, sea cucumbers, snake tails, etc. They have a round or heart-shaped body disc with five or more wrists on the body disc. Each wrist is covered with tiny tube feet that act like suction cups that help starfish move, absorb water, and grab food. Starfish have no head and tail, nor left and right sides, only above and below. They do not have sensory organs such as eyes, ears, nose, etc., nor internal organs such as hearts and lungs. They have only a simple digestive system and a complex system of water pipes. You might think starfish are clumsy and boring, but they have a lot of amazing skills.
How do starfish swim? You might think that since they are called "fish", then they must swing their bodies like fish and swim around in the water. But otherwise, starfish don't swim like fish. They also don't paddle like crustaceans or spray like octopuses. They use a unique and effective method - tube foot exercise. Tubular feet are part of the Starfish Water Pipe System, which is a suction cup-like structure that can retract and adhere.
When starfish want to move, they contract and relax the tube feet, creating a wave-like movement that moves through the water. Although this movement is not fast, it is stable and can adapt to a variety of complex terrain. For example, on rocks, coral, sand, and so on. You might ask, since they don't have eyes, how do they know their direction? In fact, there is a light sensor at the tip of each wrist that senses the direction of light in the dark and guides the starfish forward.
Let's take a look at what starfish eat. You might think that since they don't have teeth and no mouth, they must only eat something soft, finely crushed, juicey and so on. But in fact, starfish have a wide range of food, they can eat a variety of shellfish, sea cucumbers, arthropods and even small fish. You may ask, since there are no teeth, how do they chew?
Starfish have a magical and terrifying way – external digestion. When a starfish encounters a shellfish, they grab both sides of the shell with their tube feet and forcefully open a gap. They then spit their stomachs out of their mouths and stuff them into shells, directly digesting the flesh in the shells. This allows starfish to eat something much larger than their own mouth without fear of being scratched by a shell. Of course, this process is also time-consuming and laborious, and starfish can take hours or even days to complete a meal. This external digestive function of starfish makes them powerful predators in the ocean, posing a threat to many organisms.
You might think that since they have no heart, no lungs, and no blood, then they must be fragile and easily injured or killed. But otherwise, starfish have amazing regenerative abilities, and they can recover from severe trauma. For example, if one wrist is cut off, it can grow back after a while; If the entire body is cut in half, each half can grow into a new starfish; There are even starfish that can deliberately throw off a wrist as a means of defense or escape. These are all because the starfish's water pipe system and nervous system are distributed on each wrist, and as long as one wrist and part of the body disk remain, a complete individual can be regenerated. This regenerative ability makes starfish highly adaptable and survivable in nature.
Starfish are beautiful and magical creatures that play an important role in marine ecology. Some starfish are protectors of coral reefs, while others are destroyers of coral reefs. Some starfish can regenerate lost wrists or entire bodies, while others can deliberately shake off wrists as a defense. Some starfish can digest food externally, while others can devour prey much larger than themselves. The world of starfish is full of wonders and changes that are worth discovering and appreciating.