Although they aren’t technically fish, sea stars are animals that are still present in nearly every coastal habitat and can be found as low as the abyssal layer. You can identify a starfish by its bumpy skin and flat center surrounded by long limbs that give the appearance of a star. These slow-moving but sensitive fish come in a wide array of colors; although you should never pick one up, trying to find starfish along the beach is a wonderful seaside activity.
- Delicate structure: Starfish are animals that are made up of a fragile network of thin muscles and tiny ligaments. This is why they move so slowly – and also why they shouldn’t be handled.
- Extended senses: Starfish do not have a central nervous system; instead, their entire body is made up of a collection of sensory nerves. Starfish observe the world through small eyes located at the ends of their “arms.”
- Natural regeneration: Starfish possess the ability to regrow a limb that is lost. This process is slow, and it only occurs if the starfish survives the pain of the initial break. Some species of starfish can break off their own limbs in order to escape from predators.
- Vascular system: Starfish don’t actually have blood in their bodies. Instead, they pump seawater through their vascular structure in order to carry nutrients and oxygen.
The aquatic animal that is commonly known as a starfish is also frequently called a sea star. All of these animals fall into the class Asteroidea; in the scientific community, they are frequently known as asteroids. The zoological name Asteroidea translates to “star-shaped – “aster” means “star,” and “eidos” refers to “shape.”
There are over 2,000 distinct species of starfish, and more are frequently discovered during oceanic research. The many types of these animals are as varied as the different places where they are found. With so many bright colors and creative forms, it’s no surprise that so many sea stars have colloquial and zoological names that express their unique types of beauty. Some of the most notable types include:
- Common starfish: Asterias rubens is a simple, five-pointed animal with a peachy orange color. Also known as sugar starfish, you can find these aquatic animals all along the Atlantic coast.
- Sunflower starfish: Pycnopodia helianthoides is found in the Pacific ocean. These sea stars can have up to 24 limbs and come in all different types of colors.
- Royal starfish: Astropecten articulatus live in the West Atlantic. Like sugar starfish, they have five points; however, they are distinguished by their bold purple and orange colors.
- Necklace starfish: Fromia monilis are a West Pacific starfish named for the plates on their body, which look a lot like the beads on a necklace. In some areas, they’re known as tiled starfish.
- Chocolate chip sea stars: Protoreaster nodosus are found in in the Pacific ocean near Indonesia. These animals can be recognized by their black spikes, which look like chocolate chips.
Starfish are flat aquatic animals that move slowly and stick to the ocean floor. Most of them have a central disk surrounded by five or more arms. The mouth is usually located in the middle of the disk, and the ends of their arms feature light-sensitive eyespots. The skin is covered in small spines, and the bottom of its limbs are usually lined with hundreds of small tubular feet that are used for gradual movement.
Starfish love to eat mussels, but these shellfish are known for closing their shell very tightly. Even for humans, fresh live mussels are difficult to open. However, starfish can crack a mussel open by setting two of its arms on the one valve and the other arms on the other valve. The mussel will close its valves with its strong adductor, however the starfish has patience. Besides the fact that the mussel spends energy holding the adductor shut, it has closed off its source of oxygen since no water is flowing through. When the mussel starts to tire, the starfish begins to pull. After ‘fighting’ for several hours, the shell halves start to separate. The starfish will invert its stomach into the shell and digest the mussel
Normally speaking, starfish have five arms. However, you sometimes see them with fewer arms. In that case, the missing arm usually has fallen off and will later regenerate. Every once in a while, something goes wrong and instead of one arm regenerating, two arms are produced. The starfish then has 6 arms. In 2015, divers in Lake Grevelingen found a starfish with seven arms. This was even more extraordinary!
