10 Starfish Species You've Probably Never Seen Before
Starfish, or sea stars, are brilliant and resilient ocean creatures. These bottom-dwelling echinoderms have a central disc body covered in tough calcium carbonate skin that helps provide support and protection for their vital organs and complex circulatory system.
Starfish are so resilient that they can even regenerate lost arms. If a predator gets lucky and successfully bypasses a starfish's tough skin and muscles, the severed arm seals itself, and special cells migrate to the location to start growing a new limb.
These intriguing sea animals also reproduce asexually using a different regeneration ability called binary fission. Binary fission occurs when organisms divide their cells into two genetically identical daughter cells. These eggs are then mixed with sperm released into the seawater to self-fertilize.
Do Starfish Have a Brain?
Sea stars do not have a brain in the traditional sense, but they do possess "eyes" at the ends of their rays that sense visible light. This is why sea stars thrive in coral reefs and rocky coves near the surface where sunlight and warm water is abundant.
Sea Urchins: A Sea Star's Favorite Snack
Sea stars are slow and methodical predators that feast on whatever food they can track down. They use hundreds (or even thousands) of tiny tube feet to contact and entangle urchins, clams, mussels and small fish — typically other organisms that subsist on algae and phylum.
Starfish begin eating their prey by inverting their stomachs. The flexible stomach will turn inside out and extend through the mouth to infiltrate past the spines of an urchin or the shell of a clam to attack their protected internal bodies.
10 Sea Star Species You Can Find on the Ocean Floor
Making a short list of popular starfish is challenging because there are so many species to choose from — over 2,000 different species, to be precise. Here are just a few species that should satisfy your hunger for unique animal knowledge.
1. Bat Sea Star (Asterina miniata)
This is not a masked vigilante or part of the Dark Knight's arsenal, but it is a cool species of starfish. The bat sea star got its name because of the batwing-like webbing between its rays (arms). Most bat sea stars sport five appendages, but some have been known to grow over nine.
2. Brisingid Sea Star (Brisingida)
These plant-like brisingids are some of the deepest diving species, sometimes living deeper than 19,000 feet (5,791 meters) below sea level. They use their leaf-shaped arms to filter water and wait until they finally get a brief moment of substantial food from unsuspecting victims and decomposing fauna from above.
3. Crown-of-Thorns Starfish (Acanthaster planci)
If the ocean had a fashion runway, these dazzling organisms would be on it. Sporting bright, bold neon colorings and thorny upper spines, these animals are hard to miss — hope that you are lucky enough to see them and not accidentally step on these prickly fellas.
4. Granulated Sea Star (Choriaster granulatus)
It's lucky that starfish don't have ears because some of the nicknames this poor species receives would send most people into a quick depression — "cushion sea star" and "doughboy star" are just a couple.
5. Leather Star (Dermasterias imbricata)
This sea star monopolizes a large portion of available small prey in the intertidal zone. However, they don't play nicely with the next species on this list, as the morning sun star is one of its primary predators.
6. Morning Sun Star (Solaster dawsoni)
This amazing predator has 8 to 16 arms and thousands of tube feet, which it uses to fill its mouth and stomach with mussels, small fish and other sea stars.
7. Pacific Blood Star (Henricia leviuscula)
This orange-colored sea star has five slender, long arms. For this species especially, the ability to regenerate its limbs extends its life significantly, as it doesn't have as many to spare as other species.
8. Pink Sea Star (Pisaster brevispinus)
This large species can weigh up to 2 pounds (0.9 kg) and span a diameter of 2 feet (0.6 meters) wide. The pink sea star is also the inspiration for Nickelodeon's lovable animated starfish character Patrick, who stars alongside his square-pants-wearing pal, Spongebob.
9. Royal Starfish (Astropecten articulates)
The royal starfish is named for its deep royal purple skin, trimmed with a gilded orange outline along its rays. These sea stars live along rocky coastlines in North America where they manage to snare smaller animal victims, such as small fish and mollusks whole.
10. Sunflower Star (Pycnopodia helianthoides)
This species is one of the most appendage-heavy sea stars in the ocean, with roughly 24 arms that allow this predator to hunt while roaming at 3.3 feet (1 m) per hour. These starfish spend most of their lives in colder Pacific waters between Alaska and California.
Now That's a Coincidence
As a way for university faculty to provide students with positive affirmation and kudos, instructors may place some students in a flagged group for the talented and gifted. In some schools, these students are nicknamed "starfish" and are arranged into curriculum chunks covering advanced topics with deeper learning resources.
4. Some Species May Have as Many as 40 Arms
Although starfish have five-point radial symmetry, that doesn't mean all of them have five arms. "Species with 10, 20, or even 40 arms exist," says Stone, adding that if one of these arms is lost, a sea star has the amazingly ability to regenerate it. Sea stars accomplish this by housing most or all of their vital organs in their arms, which means some species can even regenerate an entirely new sea star from just one arm and a portion of the star's central disc.
The ability to regenerate lost arms is especially useful if a sea star is injured by a predator. It can lose an arm, escape and grow a new arm later. This won't happen too quickly, though; it takes about a year for an arm to grow back. Some require the central body to be intact to regenerate, but a few species can grow an entirely new sea star just from a portion of a severed limb.
5. They Have Eyes
The eyes are there, just not in the place you would expect. Sea stars have an eye spot at the end of each arm. That means a five-armed sea star has five eyes, while the 40-armed sun star has 40 eyes. Each sea star eye is very simple and looks like a red spot. It doesn't see much detail, but it can sense light and dark. And that's just enough for the environments in which these animals live.
6. Some Starfish May Live for More Than Three Decades
The average life span of a starfish is an impressive 35 years. Usually, large starfish species tend to live longer than their smaller counterparts.
7. It Is Not OK to Take Them Out of the Water
"Like many aquatic animals, sea stars get their oxygen from the water," says Stone. "They also have a unique circulatory system that pumps water through their body instead of blood, so taking them out of water for extended periods of time can stress the animal and cause them harm." Unlike fish that have gills and mammals that have lungs, she adds, sea stars "breathe" by absorbing oxygen from the water through different parts of their body, such as their skin and tube feet.
8. They Can Reproduce Sexually or Asexually
"Sea stars can reproduce sexually through spawning or asexually by dividing their central disc," says Stone. Male and female sea stars are even difficult to tell apart because they look identical. They reproduce sexually by releasing sperm and eggs (called gametes) into the water. The sperm fertilizes the gametes and produces swimming larvae, which eventually settle on the ocean floor, growing into adult sea stars. Sea stars also can reproduce asexually through regeneration, which is what happens when the animals lose an arm.
9. They Are Omnivores
Starfish eat a wide variety of plant and animal life. What they eat can depend on the species, according to Stone. "Many species are scavengers and carnivores that eat gastropods, bivalves, barnacles, marine worms and other invertebrates," she says. "Some species are suspension feeders that capture plankton and organic material from the water."
10. They Don't Swim
Sea stars use hundreds of small suction cups called tube feet on the underside of their bodies to move from one area to another. The tube feet are filled with seawater, which the sea star brings in through the madreporite (a sort of trap door) on its top side. According to the National Ocean Service, adult sunflower sea stars can move at the astonishing speed of 3 feet (around 1 meter) per minute using 15,000 tube feet. Tube feet also help sea stars hold their prey. If you get a chance, visit a tide pool or aquarium, and take a moment to watch a sea star moving around — you'll find it's truly a most amazing sight.
11. They Don't Hurt Humans, But We Are Dangerous to Them
Because they're literally shaped like stars, humans have the tendency to keep starfish as souvenirs or even hold them out of the water just for photos. Forcing starfish out of the water, or throwing them back in, is a big no-no. Just like sea cucumbers and corals, starfish are born with intricate and fragile arms and tiny body structures. Despite their regeneration capabilities, even the slightest poke may hurt or damage them, most especially when people carelessly throw them out of the water. Aside from that, human hands are naturally dangerous to all sea creatures due to billions of bacteria that exist on them and contact can lead to a possible slow death for these creatures.
Now That's Sad
The International Union for Conservation of Nature doesn't currently list any species of sea star as endangered. However, sea star wasting syndrome began causing mass die-offs of at least 21 species along much of the North American Pacific coast beginning in 2013. The disease causes the animal to lose limbs and eventually disintegrate, leaving behind a pile of white goo.
Original article: 10 Starfish Species You've Probably Never Seen Before
Copyright © 2024 HowStuffWorks, a division of InfoSpace Holdings, LLC, a System1 Company
