Although there are over 1800 differing species of starfish (Sea Stars), this article will focus on 4 unique species, which are:
THE SUNFLOWER STAR (Pycnopodia Helianthoides)
The Sunflower Star is among the largest of any starfish species. They commonly grow to over 2 ft. in diameter, weighing up to 11 pounds. However, with its 24 thick arms and large bulk, it is one of the fastest of any Sea Star species, moving at a rate of up to 18 ft. per minute. The colors of this species range widely from red to yellow, purple to pink, as well as orange and brown. This species is found from the rocky sea bottoms of Alaska, down to the California coast. They live comfortably on rock as well as mud, sand and gravel substrates. It is equipped with organs that give it both a strong sense of smell, and an extreme sensitivity to light. Sea urchins are their favorite meal, but they will also hunt and eat mussels, crabs, clams, mollusks, sponges, sea cucumbers and sand dollars. There is no noticeable difference between the male and female of this species. In fact, they do not spawn as other Sea Stars do – the males and females release their genetic material when ready, and fertilization takes place by chance. Even so, this “breeding season” takes place from May to June. The fertilized eggs float around for a while as they develop into swimming, bilateral larvae. These larvae will remain in the plankton for around 10 weeks after which they settle to the bottom and metamorphosize into a young 5-armed Star. As they grow, the juveniles first develop a single arm to one side; then add bilateral pairs of arms in a clock-wise motion.
THE CROWN OF THORNS STARFISH (Acanthaster Planci)
Also known as the “Coral-Eating Starfish” and the “Giant-Thorny Starfish”, this Sea Star is the most despised Sea Star in the world due to its destructive influence on the world’s coral reef ecosystem, especially the Great Barrier Reef where it is most abundant. It is the second largest Sea Star in the world, second only to the Giant Sunstar. They are found along coral reefs in the Pacific and Indian oceans, as well as in the Red Sea. Known as sedentary dwellers, they avoid turbulent water, preferring instead to live in more sheltered areas. These are solitary, nocturnal animals which feed alone, and seem to maintain constant distance between themselves and other members of their species. This animal can have from 10 to 20 arms, and is either greenish or brown in color. It can grow to over a foot in diameter, and despite that, moves very efficiently.
It receives its familiar name Crown of Thorns from the venomous thorn-like spikes that cover its body, making attack against this species quite difficult. The long spines are capable of piercing wetsuits (as well as skin), releasing a neurotoxin causing great pain that can last for hours. Even with these defenses however, there are a few species who attack and feed on them including the Harlequin Shrimp, the Giant Triton mollusk, the Bristle Worm, and strangely enough, one species of coral (Pseudocorynactis). Adults of the species prey mostly on coral polyps, but sometimes will go after Brittle Stars. If it is migrating, or no food is available, it can live on energy reserves for over 6 months at a time. Many scientists have stated that this species is upsetting the basis of one of the world’s most diverse ecosystems as they wipe out large areas of coral (as much as 13 square miles per year). This particular species spawn in shallow water from December to April. The timing of both egg and sperm release occur virtually simultaneously. The fertilized eggs then drift about for 2 to 3 weeks (while metamorphosis takes place) where they are commonly fed upon by reef fish. Once they enter the larval stage, they sink to the bottom; after which, transformation into 5-armed juveniles takes only 2 days. The population of these animals has greatly increased since the 1970’s. Some sources point to the decline of the reef fish population as a contributing factor.
THE CUSHION STAR
The creatures known as Cushion Stars (also known as “Bun Starfish” and the “Pincushion Star”) are actually divided into 2 very similar species, both of which are covered. They are very similar in size and shape, measuring between 12 and 18 inches. They typically have 5 tapered arms (or rays) which gives them a pentagonal shape. Both of these species are commonly dried and sold as souvenirs, however, the deep-sea variety is also eaten by some cultures.
SHALLOW-WATER (Oreaster Reticulatus)
This type of Cushion Star is widely distributed around the world. They spread across the entire Atlantic, the entire Indian Ocean, and most of the Pacific. You find these creatures in calm, shallow waters, which provide lots of sand and sea grass beds (where baby cushions like to hide). This species consists of several color types, such as red, black, brown and green. They typically feed on live coral, crab larvae, sponges, but will also scavenge as well. In subtropical regions, the males and females spawn annually (at summertime), but in tropical regions, spawning takes place year-round. Once the eggs develop into larvae, they settle into the sea grass beds (camouflaged by their greenish color), and begin to metamorphosize. This species is commonly sold in the aquarium trade although they are not recommended for coral reef aquariums, as it eats coral as well as sponges.
DEEP-WATER (Pteraster Tesselatus)
This species is found all across the Pacific, from the Alaskan Isles to America’s west coast. They are commonly found at depths ranging from 30 to 1500 feet. They have a thicker skin and relative thickness of rays than does its cousin – because of this, they are not very agile. The colors of these deep-sea dwellers include purple, brown, tan and orange. When disturbed, it often secretes a large amount of thick, viscous slime, which gives it a bad taste to predators; because of this trait, it has earned the nickname “Slime Star”. This slime in fact, is being used by scientists to develop new steroid compounds. The Slime Star is often found in the vicinity of Cloud sponges, its favorite food. He also likes scallops, sponges, hydroids, and even the bacteria that grow on mussels. Once spawning has occurred, the fertilized eggs will float in the plankton for up to 30 days, as they metamorphosize into infant starfish; after which they sink to the bottom to start their new life. It has been advised to not keep this species as a pet, because the slime it excretes is detrimental to other species, such as octopi.
THE BLUE LINCKIA (Linckia Laevigata)
This particular species of Sea Star is among the most beautiful and popular of any existing starfish. People pay a pretty penny to have one of these animals in their reef aquarium. This species (also known as the “Comet Sea Star”) is known to have originated close to the Fiji Islands, but has stretched its habitat throughout the world, finding comfortable dwellings throughout the shallower waters of the Pacific and Indian oceans. This species can grow up to a foot in diameter, and has the ability to regenerate any lost limbs at a remarkable rate. In fact, this animal can re-grow an entire new animal from almost any portion of its body that might break off. This species is not aggressive, but has very few enemies. The only true predator of this species is the Dog-Faced pufferfish; however, the Harlequin Shrimp and some species of sea anemone have been known to feed upon them.
After spawning has taken place, the fertilized eggs develop into feeding larvae within a couple of days. The larvae float around in the water for approximately a month, after which they settle down to the bottom, where metamorphosis begins. The bluish-green juveniles spend most of the day hiding in small caves or rocky overhangs, waiting for the evening to feed. Adult Linckia don’t feed as most other Sea Stars do; it attains its nutrition by slowly grazing algae, as well as other microbial matter off of rock surfaces. Although this animal is a grazer, it has also been known to scavenge a dead fish or two. Sometimes they will anchor themselves on a rock, and wave a couple of arms up in the current to gather free-floating microbes. The Blue Linckia is very popular in the aquarium pet trade, it also does very well in the sea-shell trade (where they are dried and sold as souvenirs). As a matter of fact, the souvenir trade has caused a significant decline in population. If you do choose to add a Blue Linckia to your aquarium, there are several good articles available online for the care and health of your new pet.