starfish
Discover 10 fun facts about the Sea Stars!
1. They have no brain and no blood.
Starfish use filtered sea water to pump nutrients through their nervous system.
2. They can live up to 35 years.
3. Starfish is not their right name, they should always be called Sea Star!
They’re actually related to sand dollars and sea urchins. They do not have gills, scales, or fins like fish do. So because they are not classified as fish, scientists prefer to call starfish “sea stars.”
4. There are around 2,000 species of sea star.
While many species live in tropical areas, you can also find sea stars in the cold waters of the Earth, even the polar regions.
5. They cannot survive in fresh water.
6. They can regenerate.
But its takes a while. It can take u to a year for a lost limb to grow back.
7. They eat inside out.
When they capture prey, they have tiny suction cups to grab ahold of their food. Then their stomach exits their mouth to digest the food, and reenters the body when they’re done eating. Learn more about their anatomy on our sea star web page.
Sun star with many arms. Joe Dovala / Getty Images
8. Sea Stars Reproduce Two Ways.
Male and female sea stars are hard to tell apart because they look identical. While many animal species reproduce by only one method, sea stars are a little different.
Sea stars can reproduce sexually. They do this 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 can also reproduce asexually through regeneration, such as when they lose an arm.
9. Brittle Stars are the Sea Stars’ cousins.
Brittle stars (Ophiuroidea) are a group of echinoderms that resemble starfish. There are about 1500 species of brittle stars alive today and most species inhabit marine habitats with depths greater than 1500 feet. There are a few species of shallow water brittle stars. These species live in the sand or mud just below the low tide mark. They often live amongst coral and sponges as well.
Brittle stars inhabit all the world’s oceans and live in a variety of climate regions including tropical, temperate and polar waters.
10. They can have up to 40 arms!
While you might be most familiar with the five-armed species of sea stars, not all of they have just five arms. Some species have many more arms. For instance, the sun star can have up to 40 arms
Skip to main content
Starfish are marine invertebrates. They typically have a central disc and usually five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown. Starfish have tube feet operated by a hydraulic system and a mouth at the centre of the oral or lower surface. They are opportunistic feeders and are mostly predators on benthic invertebrates. Several species have specialized feeding behaviours including eversion of their stomachs and suspension feeding. They have complex life cycles and can reproduce both sexually and asexually. Most can regenerate damaged parts or lost arms and they can shed arms as a means of defense. The Asteroidea occupy several significant ecological roles. Starfish, such as the ochre sea star (Pisaster ochraceus) and the reef sea star (Stichaster australis), have become widely known as examples of the keystone species concept in ecology. The tropical crown-of-thorns starfish (Acanthaster planci) is a voracious predator of coral throughout the Indo-Pacific region, and the Northern Pacific seastar is on the list of the World's 100 Worst Invasive Alien Species.
The fossil record for starfish is ancient, dating back to the Ordovician around 450 million years ago, but it is rather sparse, as starfish tend to disintegrate after death. Only the ossicles and spines of the animal are likely to be preserved, making remains hard to locate. With their appealing symmetrical shape, starfish have played a part in literature, legend, design and popular culture. They are sometimes collected as curios, used in design or as logos, and in some cultures, despite possible toxicity, they are eaten.
Book Now
SEA LIFE BLACKPOOL AQUARIUM LOGOToggle Navigation
Menu
Opening times today: 10am - 4pm
Tickets & Prices
Toggle Navigation
What's Inside
Toggle Navigation
Plan Your Visit
Toggle Navigation
Conservation
Schools
News
Venue Hire
Manage my booking
Home
Search
Check out
Go back to news
7 Amazing Starfish Facts
Monday 2nd July 2018
Starfish
There are over 2000 different species of starfish, these unique marine animals have various different colours, shapes, and sizes. Starfish, also known as Sea Stars, are one of the most beautiful looking animals in the vast ocean. They have a surprisingly unusual anatomy, with no brain or blood, yet are able to digest food outside their body.
Starfish can regenerate their own arms
Regenerating their own arms is perhaps one of the most useful things a starfish can do. This attribute can be used in many different ways. Arms can be lost when a starfish comes in contact with a predator, or it may be amputated in order to hide or escape from one.
Arms can take months, even years to fully regenerate, so it has to be a pretty serious situation to lose one. Incredibly, if the severed leg is not harmed, it can heal itself and even regenerate - resulting in a genetically identical starfish. Pretty cool, right?
They have no brain or blood!
With no brain or blood it seems crazy to think starfish can survive in the depth of the vast ocean. However, they find very clever and simple ways to get around it.
Seawater is pumped throughout their body as a replacement for blood, with the water delivering key nutrients to the starfish allowing its organs to function properly. The use of water saves space as there is no need for a complex blood system, also since seawater is highly abundant they will never run out of it.
Starfish may have no brain, but they are certainly not fools!
They wear tough, leathery skin
Starfish are layered with an upper skin made out of calcium carbonate. This strong material makes the skin tough and difficult for hunters to breakdown.
Some species of starfish will even go a step further with the addition of numerous spines on their skin, acting as a layer of armour to deter predators.
Starfish have eyes
Lacking a brain, blood and even a central nervous system, it might come as a surprise to you that starfish have eyes.
Just to further add to their unusual anatomy, their eyes are on the end of their arms. Whilst their eyes may not be able to see in fine detail like our eyes can, they are able to detect different shades of light allowing them to navigate their surroundings - allowing them to hunt for food and hide from predators.
Starfish move with hundreds of feet
Starfish are equipped with hundreds of tiny little feet at the end of each arm.
To move, they fill these feet with seawater, causing the arm to move like a foot would. This mechanism allows the starfish to move - much quicker than you might expect. Visit our rock pool to see this first hand!
Starfish can eat outside their body
Due to their tiny mouth on the underside of their body, starfish have adapted an ingenious way of eating things larger than it can fit in their mouth.
They have a stomach that can digest food outside their body, so that it can fit in their mouth. This allows the food to be further broken down inside the body.
Not all starfish are star shaped
Almost all starfish are shaped like a star, which is how they get their grouped name. However, there are a few special cases.
The Cushion Starfish has a round blob-like shape, while having all the genetic qualities needed to be a starfish. This starfish is actually much gentler than other starfish, feeding on detritus and plants. Other starfish will tend to feed on clams or oysters.
Comments
Post a Comment