Some starfish have up to 40 arms and can regenerate, introduction to starfish
Although starfish live underwater, they are not actually fish at all. In fact, marine scientists have replaced the common name of starfish (starfish) with the name "starfish", because starfish is not a fish.
The starfish on the map is a type of starfish called sunflower, which is a greedy predator that feeds on bivalves such as clams and mussels, and sunflower starfish is the largest starfish found in the Pacific Northwest of the United States.
So, what exactly are they? "They're an invertebrate, which means they don't have a spine," we learned in an interview with an aquarium curator. "Their bodies consist of a central disc with arms radiating outwards, and below them, there are hundreds of small suction cups called 'pipe feet' that help the starfish move around and stick to different surfaces to eat."
According to him, there are some other significant differences in the difference between starfish and fish. These cool creatures have no gills, scales, or fins; they live only in salt water; they use seawater instead of blood, pumping nutrients into their bodies through a "water vascular system."
This creature is magical, and here are 11 interesting facts about these echinoderms that you may not know.
1. They first existed millions of years ago
"Starfish belong to a group of marine invertebrates called echinoderms that first appeared more than 500 million years ago, and the ancestors of modern starfish appeared in the Ordovician period more than 450 million years ago." Echinoderms include five categories of marine life: starfish; brittle and basket stars; sea urchins and sand money; sea cucumbers; and sea lilies and feathered stars.
2. There are about 2,000 different species
"They can be found in a variety of habitats from shallow sand bottoms and cold rocky environments to the bottom of the sea," the curator said. Some starfish have even been found on the sandy seabed at depths of 29,500 feet (9,000 meters)! One of the most unique, the crown of thorns starfish, a tropical species found in the Pacific and Indo-Pacific Oceans, is named after the long spines that cover its body. Starfish's spines consist of calcium carbonate plates with tiny spines on their surfaces that are used to protect them from predators, including birds, fish, and sea otters.
3. The mouth of the starfish is under the body
When catching food (usually bivalves such as clams or mussels) with its tube feet, the starfish wraps its arms around the animal's shell and pulls it apart slightly. The starfish then pushes its stomach from its own mouth into the shell of its prey. It then digests the animal and slides its stomach back into its own body. This unique feeding mechanism allows starfish to eat prey larger than its small mouth. Favorites on other starfish menus: mollusks such as clams, oysters and snails.
4. Some species may have as many as 40 arms
Although starfish have a five-point radial symmetry, that doesn't mean they all have five arms. "There are species with 10, 20 or even 40 arms," the curator said, adding that if one of the arms is lost, starfish have an amazing ability to regenerate. Starfish achieve this by housing most or all of their vital organs in their arms, which means that some species can even regenerate an entirely new starfish from just one arm and part of the central disk.
If a starfish is injured by a predator, the ability to regenerate the lost arm is particularly useful. It may lose one arm, then escape and grow a new one. However, this is not going to happen anytime soon. It takes about a year for an arm to grow back. Some require a complete central body to regenerate, but a few species can grow entirely new starfish from only a portion of the amputated limb.
5. They have eyes
The eyes are there, just not where you expect them to be. Starfish have an eye spot at the end of each arm. This means that a five-armed starfish has five eyes, while a 40-armed sun star has 40 eyes. Each starfish's eye is very simple and looks like a red dot. It doesn't see much detail, but it can sense light and darkness. This is enough for the environment in which these animals live.
6. Some starfish may have a lifespan of more than 3 years
The average lifespan of a starfish is an impressive 35 years. In general, large starfish species tend to live longer than their smaller counterparts.
7. They cannot be taken out of the water
"Like many aquatic animals, starfish take oxygen from the water, and they also have a unique circulatory system that pumps water through their bodies rather than blood, so removing them from the water for long periods of time can put pressure on the animals and cause harm to them." Unlike gills and mammals with lungs, starfish "breathe" by absorbing oxygen from water through different parts of the body, such as skin and tube feet, she added.
8. They can reproduce sexually or asexually
"Starfish can reproduce sexually by laying eggs or by splitting their central discs," and male and female starfish are even difficult to distinguish because they look the same. They reproduce sexually by releasing sperm and eggs (called gametes) into water. Sperm fertilize gametes and produce swimming larvae, which eventually settle on the ocean floor and grow into adult starfish. Starfish can also reproduce asexually by regenerating, which happens when an animal loses an arm.
9. They are omnivores
Starfish eat a wide variety of plants and animals. What they eat depends on the species. "Many species are scavengers and carnivores that eat gastropods, bivalves, barnacles, marine worms and other invertebrates," she said. "Some species are suspension keepers who can capture plankton and organic matter from the water."
10. They can't swim
Starfish use hundreds of small suction cups called pins under its body to move from one area to another. The foot of the tube is filled with seawater, which starfish brings in through a trapdoor at its top. According to the survey, adult sunflower starfish can move at an astonishing speed of 3 feet (about 1 meter) per minute using 15,000 tube feet. The tube feet can also help starfish catch prey. If you get the chance, visit the tide pool or aquarium and take a moment to watch the starfish move around – you'll find that this is truly one of the most stunning sights.
11. They don't hurt humans, but we're dangerous to them
Because their shape does resemble stars, humans tend to use starfish as souvenirs, even placing them in the water just to take pictures. Driving starfish out of the water, or throwing them back, is a big no-no. Like sea cucumbers and corals, starfish are born with complex and fragile arms and tiny body structures. Despite their regenerative abilities, even the slightest poke can hurt or damage them, especially when people accidentally throw them out of the water. In addition to this, human hands are naturally dangerous for all marine life, as there are billions of species of bacteria present on them, and contact can cause these creatures to die slowly.