Around the world, there are over two thousand species of starfish. They live in all sorts of oceanic environments, and thrive. From the deep blue sea, to rock pools and beaches, starfish continue to flourish in their varied habitats. The starfish is strictly aquatic, and will die if it is left out of the water for too long. Depending on its species, the starfish may enjoy “tropical climates to the cold seafloor” (Doubilet 2012, 1
). However, the water they live in must be saltwater. There are no freshwater starfish species, and their bodies won’t function in freshwater. Their bodies are especially adapted to saltwater, and even use “sea water instead of blood to pump nutrients throughout their bodies” (Doubilet 2012, 2
The starfish is not, however, a fish. It is an echinoderm. Echinoderms are “primarily bottom dwelling creatures” (Klappenbach 2012, 3) and have spiny-skin. Some other echinoderms include sea urchins, sea cucumbers and sand dollars. Due to this fact, scientists have decided to throw out the beloved ‘starfish’ name, and replace it with ‘sea star’. But, it is an uphill battle, since so many people are used to the term ‘starfish’. The most common starfish, the Asterias rubens
, is the poster child for starfish everywhere. It is colored the common orangeish-pinkish hue, and has the staple five legs. And its classification is pretty simple, too. The common starfish is from the Animilia kingdom. Its phylum is Echinodermata Asterozoa, and is from the Asteroided class. The order is Forcipulatida and is a part of the Asteriidae family. Its genus is Asterias
and is the A. rubens
All starfish have the same basic shape. As suggested by its name, the starfish is shaped like, well, a star. However, do not be fooled. Not all starfish only have five legs. They may have been named for five arms, but there can be many more. The number of arms range “from the familiar five armed specimen to its 40-armed cousin” (Brower 2011, 4). Their “bodies grow outward in a radial pattern” (Brower 2011, 5) and the center is rounded. The starfish is protected by its spiny, hard skin that covers its top. They are usually brightly colored; yellow, red, pink and orange are found to be the most popular coloring.
Starfish have no backbone; instead they have hard plates under the surface of their tough skin. In some cases, these hard plates have spines. For some, they do not. This is one of the many reasons that the starfish has been classified as an echinoderm. “Echinoderms serve as hosts to a large variety of symbiotic organisms including shrimps, crabs, worms, snails and even fishes” (Zubi 2010, 6
). Starfish, although perfectly functional, have no brain. The starfish also lacks eyes, a nose and a head. But, starfish do have a way to ‘smell’ their prey. They have sensitive cells covering their skin, some of which can detect chemicals put off from prey.
Sometimes, the starfish’s magnificent body can be used to serve human needs. Some fertilizer companies have hundreds of starfish harvested. They take a large mop-like tool, and drag it along the seafloor. The starfish are gathered up, after attaching to the net, and are hauled aboard the boat. Once the harvesters have collected enough starfish, they “are grounded up and sold for fertilizer and poultry feed” (Zabel 1998, 7
The starfish truly has some amazing adaptations and skills that have been carefully honed over the many years. Now, picture this: there is a common starfish (Asterias rubens
) attached to a rock. Now, there is a sea bird flying overhead, and spots the orange starfish. The bird swoops down and, with its long beak, is able to pry the starfish loose, and eats it whole. Well, with the exception of one of the starfish’s arms. The sea bird flies away, satisfied. And the poor starfish is dead, right? Wrong. Over the process of the next couple of days, that one leg can regenerate a whole new body for the starfish. Because, the starfish only needs one fifth of its body to be able to regenerate what was lost. That is one of the two major defenses that each starfish has. It’s second is the bony skin it was born with, and its uncanny ability to hide. The starfish eats a variety of the other organisms. Since the starfish is carnivorous, its diet includes mussels, clams, coral and even other starfish. Starfish are “ruthless carnivores and frequently cannibals” (Brower 2011, 8
Not only do they have no problems when it comes to feeding, but starfish also have some pretty handy survival techniques up their sleeves. Starfish are often stuck on beaches after bad storms. When this happens, while they wait for the tide to reclaim them, they need to stay cool. The starfish “pumps itself up with cold seawater to lower its body temperature” (Bourton 2009, 9
). Some starfish, such as the Crown of Thorns starfish, has venomous spikes that protrude from its body. The starfish has another peculiar adaptation to add to its arsenal. You see, unlike Patrick Star, starfish have a rather unusual way of eating. For many starfish species their ‘cardiac stomach’ is extended outside of their body. There, the stomach secretes digestive enzymes that break down their prey. However, some are “suspension feeding starfish (…) their tube feet pass food to the mouth” (Dale 2000, 10
). The mouth of the starfish is located underneath the body in the center.
The starfish is usually classified as a keystone species. The starfish preys, usually on mussels, and without the starfish, the mussel population would spiral out of control. On the other hand, the starfish is sometimes the species that needs to be kept in check. For example, the Triton Trumpet Snail preys on the Crown of Thorns starfish. An experiment was done where all of the Triton Trumpet Snails were removed and, as a result, the Crown of Thorns starfish population spiraled out of control. The starfish is usually the one keeping things light, just like how the Triton Trumpet Snail “is pivotal in maintaining a healthy reef environment” (Brower 2011, 11
Another interesting part of the starfish is the fact that all of its major organs are dispersed around the body. Not all of the organs are located in the center of the starfish’s body, but also in the starfish’s arms. It is another amazing defense that the starfish possesses. That way, no matter what part of the body is eaten, there will always be enough to regenerate, if needed. Sometimes there can be too much of a good thing, though. There are cases where a starfish grows two arms in place of the original. That can be both good and bad news for the starfish. It means that the extra limb could slow them down, however it gives them more of an opportunity to regenerate if it came down to it. The starfish is famous for this ability, due to the oddness and unexpectedness. That is one of the main reasons that they are able to survive for so long, though. And, honestly, who would not want to be able to grow their limbs back, anyways? How cool would it be if someone who needed an amputation could just grow a new, unaffected arm back in its place in a matter of days? “Sea stars are always in danger of losing arms, so being able to grow new ones is important to them” (Planet 2012, 12
). Imagine how important it could be for humans if scientists somehow figured out how to harness that ability. So many devastating things could be fixed so easily. And, people would never have to recuperate, and learn how to live with fake appendages.
Although scientists are far from trying to figure something so difficult out, they are learning from starfish right now. In the December of 2010, an article was written about a group of scientists began to take interest in starfish that “could hold the key to finding a new treatment for inflammatory conditions such as asthma, hay fever and arthritis” (Morelle 2010, 13
). They were especially interested in Marthasterias glacialis
, or better known as the Spiny Starfish. They are especially interested in the “slimy goo that covers its body” (Morelle 2010, 14
). They look to the Spiny Starfish because, although most man-made structures get caked with marine life, starfish keep their surface clear. Dr. Charlie Bavington, from a marine biotechnology company (GlycoMar) “explained: “Starfish live in the sea, and are bathed in a solution of bacteria, larvae, viruses and all sorts of things that are looking for somewhere to live” but, starfish have a very “efficient anti-fouling surface” which allows them to prevent icky things from sticking to them (Morelle 2012, 15
). The non-stick property is what grabbed their attention, and would especially help with inflammatory conditions. However, this unlikely candidate from the Seas of Scotland may take a while to contribute to a medical breakthrough. All of the pieces are coming together, its just a means of getting a medication suitable for testing. But, the spiny starfish definitely presents an amazing opportunity for the field of medicine and inflammatory treatments for future patients.
The Echinodermata species has a very "extensive fossil record tracing echinoderm evolution" (Fossil Museum 2012, 17
). There is evidence supporting the theory that brittle stars and sea stars are closely related, however there isn't enough proof found for scientists to confirm this fact. There is definitely evidence that points towards "starfish and brittle stars probably diverged from a common somasteroid ancestor" (Fossil Museum 2012, 18
), but there is still no definitive proof that has been brought to light in the scientific community, as of now. Because, although there is lots of evidence supporting this idea, the "poor fossilization" (Fossil Museum 2012, 19
) keeps scientists from fully proving this. Because "complete fossil starfish are also very rare" (Fossil Museum 2012, 20
) so scientists cannot compare the brittle stars and sea stars at the 'point of divergence' due to the lack of complete fossilized starfish skeletons. But, scientists have found that sea stars are related to sea cucumbers, urchins and, possibly, closely related to brittle stars.
Personally, I have never actually been attacked by a vicious starfish. And neither of my parents has been killed by a man-eating starfish. However, I did grow up with starfish. I would go to the aquariums, and different science center, and play with the starfish in the tide pools. Also, who couldn’t forget about Mr. Patrick Star? I grew up with Spongebob Squarepants’ best friend. He lives under a rock in Bikini Bottom with his best friends: Spongebob, Sandy, Squidward and Mr. Krabs. Although Patrick is absolutely nothing like real life starfish, he is the reason that I chose to do my report on starfish. This is for you buddy!
My favorite video: (also explains how i feel finishing this essay)
Brower, Jessica. "Animals That Feed on Sea Stars." EHow. Demand Media, 08 June 2011. Web. 16 Apr. 2012. <http://www.ehow.com/info_8563560_animals-feed-sea-stars.html>.
Dale. "Starfish Digestion and Circulation." Madreporite Nexus. 2000. Web. 16 Apr. 2012. <http://www.madreporite.com/science/digest.htm>.
Doubilet. "Starfish (Sea Star)." Animal. National Geographic, 2012. Web. 15 Apr. 2012. <http://animals.nationalgeographic.com/animals/invertebrates/starfish/>.
Fossil Museum. "Echinodermata - Echinoderms." Phylum Echinodermata. Fossil Museum, 2012. Web. 10 May 2012. <http://www.fossilmuseum.net/Tree_of_Life/Phylum-Echinodermata.htm>.
Klappenbach. "Echinoderms." Animals / Wildlife. About.Com, 2012. Web. 17 Apr. 2012. <http://animals.about.com/od/echinoderms/p/echinoderms.htm>.
Morelle, Rebecca. "Could Starfish Inspire New Cure for Inflammation?" BBC News. BBC, 12 Sept. 2010. Web. 19 Apr. 2012. <http://www.bbc.co.uk/news/science-environment-11931039>.
Planet, Animal. "Starfish." Animal Planet, 2012. Web. 18 Apr. 2012. <http://animals.howstuffworks.com/marine-life/starfish-info.htm>.