Feather Star

The feather star is a dazzling animal whose unique appearance has caught the attention of people around the world. Their otherworldly appearance has even been compared to biblical angels. Their beauty notwithstanding, these admirable creatures contribute greatly to their environment, as well as to the ecosystem.

Feather Star Facts

• Feather stars eat with their feet. They have sticky mucus that helps them catch their microscopic prey before flinging it into their mouths.
• Feather stars are considered to be one of the most amazing and unique sea creatures because they look like plants. They have beautiful feathery arms that may look weird and awesome all at once.
• Feather stars have pentameral symmetry. This means that their bodies are patterned in fives or multiples of fives.
• Feather stars don’t have true stomachs. Their food goes through their esophagus and straight to their intestine.
• Feather stars don’t have hearts, eyes, or a brain.

Feather Star Evolution and History

Feather stars belong to the phylum Echinodermata. The echinoderms are believed to have appeared about 540 million years ago during the early Cambrian Epoch.

Feather stars also belong to the class, Crinoidea, whose oldest known members can be traced back all the way to the Ordovician period, 480 million years ago. These crinoids experienced an important diversification during the Triassic period, 230 million years ago, when they evolved flexible limbs and freedom of movement. However, they almost went extinct at the end of the Permian Epoch.

Crinoid fossils are very prevalent throughout nature and are often found in sedimentary rocks. A fossil named Calpiocrinus intermedius was found from the Silurian Period of England and dates back to about 420 million years ago. The largest known crinoid fossil had a stem that measured 130 feet in length!

Feather stars only have stalks in their juvenile stage of development. In the past, during the Paleozoic Era, 245 to 570 million years ago, stalked crinoids usually lived in shallow water without too much fear of the predators because the predators weren’t as advanced as they are now. Now, with bony fishes as predators, the sea lilies and juvenile feather stars remain stalked on the sea floor, where there is no sunlight, and their predators can’t see them.

Feather Star Scientific Name

Feather stars belong to the class Crinoidea and phylum Echinodermata, along with other marine creatures such as sea stars and sea urchins. They also constitute the order Comatulida, which also happens to be the largest order of crinoids.

The class name Crinoidea originates from an Ancient Greek word krinon, meaning “a lily”, which alludes to the resemblance of the animal to the lily flower. Crinoids are called sea lilies if they are affixed to the sea floor in their adult stage through the means of a stalk. The crinoids that do not usually have stalks and freely swim in the ocean are called feather stars.

There are about 700 species of crinoids alive today, and 550 of them are feather stars.

Feather Star Appearance

Feather stars are stunning creatures to observe. They have a light, feathery appearance that is quite ethereal and can be easily mistaken for plants. These unique creatures come in a variety of colors, such as purple, red, black, green, white, black, or in a colorful pattern. Usually, the deeper the star’s habitat is, the paler its color.

Just like all other echinoderms, they have pentameral symmetry, which means that their parts occur in patterns of five or multiples of five. While some crinoids have just five arms, most of them have more arms that occur in multiples of five. The arms of feather stars are about 0.4 to 14 inches long.

Feather Star Anatomy

Feather stars consist of a stem or stalk, which is present in juveniles and absent in adults, and a crown, which has a cup-shaped body called the theca. They have calcite plates called ossicles embedded in their skin, which feel rough to the touch. The base of the theca is called the calyx, from which forms a cup-like group of ossicles. The stem is used to attach itself to hard surfaces before its adulthood and can reach up to three feet in length.

Their arms are long and contain feathery branches called pinnules. Depending on where they live, these arms could be longer. If the star lives in an environment where there is enough plankton, then they have shorter arms. However, if they live in an environment with not enough food resources, then their arms tend to be longer. This is an adaptation to catch food more easily. The feather star’s arms are also covered with sticky mucus, which is perfect for trapping food particles.

The arms of feather stars are specialized for different things. The ones called “cirri” are responsible for clutching onto solid surfaces to perch on during feeding. Their mouths are located on the theca along with the anus.

Feather Star Behavior

Feather stars tend to be nocturnal animals. They live in clusters in coral reefs. During the day, they hide in the reefs, keeping out of sight. In the night, they crawl out partially or fully and latch onto the heads of the coral to feed. The juvenile feather stars that still have their stalks attached do not observe this way of life because they are usually at the bottom of the sea, where there is little to no sunlight.

Feather stars can also regenerate broken or lost body parts just like starfish. They can regrow arms that have been maimed by predators or lost in harsh environmental conditions. With just one arm left and an intact nerve center, these animals can regrow all of their missing limbs.

These crinoids move with the use of their arms. They can swim, crawl, and even descend by waving their arms.

Feather stars are known to form symbiotic relationships with other sea creatures such as sea snails, lobsters, shrimp, and fish. The feather star acts as the host to these animals, providing them with shelter and safety from predators. In return, the small animals groom the star by picking off pieces of debris and detritus from its body.

Feather Star Diet

They feed on microscopic organisms such as plankton and also on ocean detritus. While it may be gross for people to eat with their feet, it is perfectly normal for feather stars. This is possible because their arms are coated with sticky mucus, which locks in particles from all around them. They feed by holding up their arms against the water current in a fan-like shape and catch the food with their longest tube feet. When they’ve caught a food particle, they send it to the ambulacral groove, which contains cilia, and the cilia eventually transport it into their mouths. The feather stars may also settle on hard surfaces like rocks or the coral while feeding for better balance.

Feather stars don’t have actual stomachs. Their mouth connects to their short esophagus, which, in turn, connects to their intestine.

Feather Star Habitat and Population

Feather stars are marine animals. They inhabit the waters of the Caribbean Sea, the Atlantic Ocean, the Antarctic waters, the Indian Ocean, and the South Pacific Ocean. If you are trying to spot these creatures, then you might have to give up hope because they are incredibly difficult to sight. This is because they live deep down in the sea. Feather stars mostly live on coral reefs, whereas sea lilies are attached to the ocean floor. Feather stars are typically found from shallow waters down to about 1,250 meters (4,100 feet), while some stalked crinoids (sea lilies) have been found at depths up to 9,000 meters (about 30,000 feet).

Feather stars lose their stalks during the larval stage of their development, so they usually creep around the coral reef during the night, feeding on plankton and detritus. Don’t expect to find these dazzling creatures on the beach either. They live too far down to ever even wash up on shore. When they die, their bodies stay on their reef habitat and don’t wash up on shore.

They are not currently listed on the IUCN List of Endangered Species. They are not considered to be a threatened group.

Feather Star Reproduction and Lifespan

Feather stars, just like other crinoids, do not reproduce through cloning, unlike some echinoderms such as sea stars. Instead, they have distinct sexes with each being either male or female. The reproductive genitals are usually located in the pinnules nearest to the crown in most species. However, in some crinoid species, they are located in the arms.

The pinnules ultimately discharge the eggs and the sperm into the environment by rupturing. In some types of crinoids, though, the fertilized eggs are bonded to the arms by a substance that is secreted by glands in the epidermal layer of their bodies. In some other crinoid species, particularly those that live in the cold Antarctic waters, the eggs are kept in sacs located on the pinnules or the arms.

The eggs hatch out free-swimming bilaterally symmetrical larvae. These larvae do not eat. After a few days, they latch on to the sea floor and transform into a radially symmetrical stalked juvenile through metamorphosis.

Once they become adults, they lose their stalks and become free-swimming agents. Feather stars are sexually mature at 12 to 18 months old. They have an average lifespan of 15 years.

Feather Star Predators and Threats

Feather stars are not known to have many natural predators, mostly due to their choice of habitat deep in the sea, as well as the fact that they don’t taste very good. Their bodies are mostly made up of calcium carbonate, which a lot of predators don’t find appealing. Since there is a low amount of filtered sunlight down there, not a lot of predatory creatures can be found in their habitat.

However, studies conducted on a species of sea urchin, Calocidaris micans, revealed some amounts of crinoid stalk in their digestive system. This sea urchin also lives in the same area where the sea lilies inhabit. Because of these facts, it is speculated that the sea urchin could be a potential predator of crinoids.

Some fish still prey on them and can pick off pieces of their arms. Thanks to their regenerative ability, these limbs can still grow back.