Royal Starfish

Astropecten articulatus

Today's animal is the Royal Starfish, an Echinoderm that gets its name from it's royal purple coloration. These five armed creatures sport bright orange marginal plates, with a deep blue or purple interior. Quite the color combination!

The eastern coast of the United States is where the Royal Starfish calls home. Their normal habitat is the continental shelf, typically between 0 and 30 meters down.

It can be hard to imagine such a sedentary creature being a predator, but the Royal Starfish certainly is! They snatch up mollusks with their arms, and then guide the prey to the mouth cavity, where the prey is swallowed whole!

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IUCN Status : Not listed
Location : East coast of the United States
Size : Arm length up to 4in (9cm)

Classification : Phylum : Echinodermata -- - Class : Asteroidea -- Order : Paxillosida
Family : Astropectinidae -- Genus : Astropecten -- Species : A. articulatus
Image : Project Noah

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Common Comet Star

Linckia guildingii

The Common Comet Star is a Sea Star found in the warm, tropical waters of the Atlantic, Pacific, and Indian Oceans. They grow 4-7 arms that can reach about 8in in length each, and are generally grey in color, though reds, purples, and oranges are also found.

These Starfish are especially interesting because of their regenerating arms. Most Starfish can regenerate a broken limb, but the Common Comet Star can regenerate an entire new animal! If an arm breaks off, it is called a "Comet." Comets can move about on their own, and can slowly grow more arms until a whole new Starfish is generated. The process can take up to six months to complete!

The Common Comet Stars are also able to reproduce sexually, with males and females releasing sperm and eggs in order to spawn.

When it comes to feeding, the Common Comet Stars are actually able to exvert their stomachs. This means that instead of eating their food and having the digestive juices break it down internally, they excrete their digestive juices and break down the food first... and then eat it. They primarily consume algae and bacteria  but will also eat dead sea creatures.

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IUCN Status : Not Listed
Location : Tropical Oceans
Size : Arm length up to 22cm

Classification : Phylum : Echinodermata -- Class : Asteroidea -- Order : Valvatida
Family : Ophidiasteridae -- Genus : Linckia -- Species : L. guildingii
Image :  USCA

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Chocolate Chip Sea Star

Protoreaster nodosus

It's no wonder how the Chocolate Chip Sea Star got its name. These tropical echinoderms have creamy, brownish bodies topped with dark brown tubercles all over the top, making them resemble the popular cookie!

You can find Chocolate Chip Sea Stars in the shallow waters of the Indian and Pacific Oceans, hanging out in sandy beds and near coral reefs.

Sea Stars have no eyes, so they must find they prey using their sense of smell. Chocolate Chips aren't picky about what they eat, so their meals can range from live sea aponges, to coral, to the waste of other animals. When they find some food, they actually push their stomach outside of their mouth, engulf the meal, and then bring it back inside their body!

The species has the ability to reproduce both sexually and asexually. Sexual reproduction is done externally-- the eggs and sperm are released into the water at the same time, where they mix and fertilize. The Sea Stars can also reproduce asexually, making exact copies of themselves through regeneration. If they lose an arm, they can grow it back. But that chunk of lost arm can also grow a whole new Sea Star! Baby Chocolate Chip Sea Stars go through five growth phases over 2 years, when they finally reach adult size and become sexually mature.

Chocolate Chip Sea Stars are sometimes kept in aquariums, due to their appearance and non-aggressive behavior. Keeping them with coral is probably a bad idea though, since they will eat it!

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IUCN Status : Not Listed
Location : Pacific and Indian Oceans
Size : Length up to 16in (40cm)

Classification : Phylum : Echinodermata -- Class : Asteroidea -- Order : Valvatida
Family : Oreasteridae -- Genus : Protoreaster -- Species : P. nodosus

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Helicoplacus

Helicoplacus

Today's animal might just be the oldest creature I've ever talked about. It lived in the early Cambrian period around 525 million years ago!

Helicoplacus is the genus name for two species of absolutely ancient Echinoderm. They are the earliest Echinoderm fossils that have ever been studied, and the specimens are pretty well preserved for being half a billion years old!

Helicoplacus species had skinny pine-cone shaped bodies that were vertically oriented and attached to the sea floor. They had very primitive respiratory systems, and there is dispute about where the mouth actually was. It is believed that the grooves that circled the bodies actually helped move food into a mouth, wherever it was placed.

Members of the genus lived for around 15 million years before going extinct.

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Status : Extinct for over 500 million years
Location : Fossils found in North America
Size : Length up to 2.8in (7cm)

Classification : Phylum : Echinodermata -- Class : †Helicoplacoidea -- Genus : Helicoplacus

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Brittlestar

Brittlestar

Invertebrates can be difficult to write about. There are literally hundreds of thousands of species! To compare, there are only 50,000 members in the Chordata phylum, but almost 1,000,000 Arthropods! And that doesn't include the Nematodes, Molluscs, Annelids, and the 30-somethings other Invertebrate phyla out there!

Unfortunately, even though there are way, way more invertebrates, it can be incredibly difficult to find exact information about a single species. To be fair, some are quite prolific- like the American Lobster, Black Widow, and Common Octopus. But other times it is difficult to say much about an entire family, much less a specific genus or species.

Such is the case today with the Brittlestar. There are close to 2,000 species within the Ophiurida order, and they can be found in oceans worldwide. Not only is their geographic range huge, but they also live in many different ocean environments, from shallow coasts to deep sea floors!

Brittlestars are named for their starfish-like bodies and long, stringy arms that break away easily when they are under attack. Don't worry, the arms grow back! They are also very fast movers, and tend to come in camouflaging colors. These are excellent traits to have when you have literally dozens, if not hundreds of predators.

Brittlestars, and many other invertebrates, are so interesting because they are so very different anatomically from more familiar critters. They don't have brains! Their mouth and anus are the same exact orifice! They sense light and smells through their feet! Some of them are even bioluminescent! Most species feed on floating debris that they grab using their arms and transport to their central organs, but some also make use their tooth-ringed mouth/anuses to feed on small animals.

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Location : Worldwide
Size : Typical body diameter around 1in (2.5cm)

Classification : Phylum : Echinodermata -- Class : Ophiuroidea -- Order : Ophiurida

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Crown-of-Thorns Starfish

Acanthaster planci

The Crown-of-Thorns Starfish is a very large sea star, sporting diameters of up to 20 inches across. They are actually the second largest of all the Sea Stars, beaten only by the massive, nearly meter wide Sunflower Starfish. Crown-of-Thorns Starfish can be found in the Indian and Pacific oceans, as well as in the Red Sea. They are solitary creatures, and live on Coral Reefs.

 Crown-of-Thorns Starfish get their name from the massive spines that grow out of their body. These spines are capable of piercing diving suits, and are full of a neurotoxin that can cause severe pain and swelling in humans. Coral plays a huge part in this Starfish’s life. They are predators that feed off of the Coral Polyps, and their choice of meal can cause huge amounts of damage to the reefs. They pose one of the greatest natural threats to the Great Barrier Reef, for example, because they can feed on Coral faster than the Coral can grow back.

Outbreaks of the Crown-of-Thorns Starfish happen in part because they don’t have too many natural predators, and many of those creatures that do feed on them are overfished. Another reason for the infestations deals with the health of the reefs themselves. Erosion and agricultural runoff has caused reefs to decline in health, which means they aren’t able to consume the Starfish are quickly when they are in their larval phase.

 Efforts have been made to remove and kill Crown-of-Thorns Starfish, but they are tricky to get rid of, since they can regenerate from severed limbs! One method that has had some effectiveness is injecting the Starfish with sodium bisulfate, which is lethal to them but causes no damage to the surrounding reef. Physical removal is also sometimes carried out, but it is more difficult to manage as the Starfish are able to poke through the divers’ wetsuits.

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IUCN Status : Not Listed

Location : Indian and Pacific Oceans

Size : Diameter up to 20in (50cm)

Classification : Phylum : Echinodermata -- Class : Asteroidea -- Order : Valvatida
Family : Acanthasteridae -- Genus : Acanthaster -- Species : A. planci

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Sand Dollar

Dendraster excentricus

There are many, many different species of Sand Dollar. In fact, these interesting invertebrates have an entire order to themselves! Sand Dollars typically measure only a few inches in diameter, and come in all different colors, depending on the species.

Sand Dollars can be found in oceans around the world. Though you will often find them on beaches, they actually live out in coastal waters. The specimens that you pick up are skeletons of dead sand Dollars that have washed ashore.

Though we think of Sand Dollars as smooth white disks, in life they can actually be quite prickly looking! They have a skin of tiny spines that helps them to burrow and move. They also have tube feet on both the top and bottom, and, like all Echinoderms, they display radial symmetry.

The Sand Dollar has its mouth on the underside of its body. They use their tube feet to sift through the side and direct their tiny meals into the mouth part.

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IUCN Status : Not Listed

Location : Oceans Worldwide

Size : Width around 4in (10cm)

Classification : Phylum : Echinodermata -- Class : Echinoidea -- Order : Clypeasteroida

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Sea Cucumber

(Image Source)

There are over 1,200 known species of Sea Cucumber, invertebrate echinoderms of the class Holothroidea. All species are ocean-dwellers, living in waters throughout the world, including the frigid waters near the North and South Pole. They come in a variety of sizes and colors, with the largest (the appropriately named Giant Sea Cucumber) measuring up to several feet in length. Because of their soft bodies, Sea Cucumbers have not fossilized well, but we do have examples dating back around 400 million years to the Silurian.

Sea Cucumbers are scavengers, feeding off of plankton and debris that floats through the water. They draw meals in using tentacle-like appendages around their mouth, and then digest and expel the waste back into the water, where it becomes food for bacteria. Most Sea Cucumber species have very tiny tube-like feet that help them to move slowly.

One of the most interesting (and probably disgusting) habits of Sea Cucumbers is their ability to ward offthreats. Many species will dispel their internal organs out of their anus, distracting the predators and making themselves smaller. They are then able to regrow those organs. Sea Cucumbers also have an an additional tactic up their proverbial sleeves. They can shoot out a sticky mucus that ensnares attackers.

(Image Source)

Sea Cucumbers reproduce both sexually and asexually, depending on the species. Sexual reproduction happens externally, with the sperm and egg intermingling in open water.

Some species of Sea Cucumber are harvested as delicacies in a fishing process known as Trepanging.

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