Protoreaster nodosus
Encyclopedia
Protoreaster nodosus is a species of sea star
found in the warm, shallow waters of the Indo-Pacific
region. Also known as "horned" or "Chocolate Chip" sea stars, they possess rows of spines or "horns"; black conical points arranged in a single row, radially on the dorsal side, which may erode and becoming blunt. These dark protrusions are used to scare away possible predators, by looking frightening or dangerous. On the ventral side, tube feet
, purple in color (or pale, transparent pink), are arranged in rows on each arm. Most horned sea stars found are a roughly rigid five-pointed star-shape with tapering arms to the end, although there are anomalies like four or six-armed specimens; they may grow up to 30 centimetres in diameter. The sea stars are usually colored in shades of red or brown, but can be light tan, the color of cookie dough. This appearance, combined with the small horns on its dorsal side, give the sea star a look similar to that of a bumpy cookie. Horned sea stars prefer sheltered, sand
y or slightly mud
dy bottoms more than hard substrata such as coral reef
, and are frequently sighted conspicuously between the leaves of seagrasses on sea grass meadows or on blank stretch of coral sand. In shallow water, this species can be seen intertidally, occasionally exposed to the low tide. they do not withstand rapid changes well, however, and usually keep themselves underwater. In aquariums, these sea stars like to climb around on glass and also filters, which they can disrupt. Sometimes, many individuals of this species can be seen gathering on soft bottom with reason not very well known, probably to increase the chance of fertilization when spawning or simply a suitable feeding ground.
Horned sea stars seem to be opportunistic carnivores; adults are known to predate on most sessile life forms including hard coral
s and sponge
s in aquarium. In this same setting, they will hunt down snails and eat them. An individual of horned sea star also has been observed eating a sea urchin
in their natural habitat. In public aquarium
s, these stars are sometimes target-fed with chopped squid
s, clam
s or shrimp
s, and are popular animals for touch pools as it is moderately large in number in some undisturbed areas. Horned sea stars need perfect water condition, suitable diet and proper acclimatization to thrive - thus, these sea stars did not fare very well, caused by several factors mentioned before in many home aquariums. In reef aquariums, they are regarded as undesirable as they have destructive tendencies of toppling decors and digesting patches of corals and sessile organisms; they are reasonably safe if kept in a fish-only aquarium. However, the sea stars are desirable for their cute appearance and relatively non-aggressive behavior.
In many tropical Asia
n and Pacific countries, horned sea stars are collected for sea shell trade
for their ornate skeletons. In some areas overharvesting is an issue and reduces greatly the population of the echinoderms. Related to this species, the Atlantic Oreaster reticulatus
, commonly known as Bahama Sea Star, is also a previously abundant species reduced in number due to the continuous harvesting by the industry and tourists alike.
As with other tropical echinoderms, commensal animals like shrimps (of genus Periclimenes), tiny brittle star
s and even juvenile filefish
can be found on the surfaces of a horned sea star. This may be attributed to its protective nature, as there are few predators that would dare to eat this echinoderm.
Sea star
Starfish or sea stars are echinoderms belonging to the class Asteroidea. The names "starfish" and "sea star" essentially refer to members of the class Asteroidea...
found in the warm, shallow waters of the Indo-Pacific
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
region. Also known as "horned" or "Chocolate Chip" sea stars, they possess rows of spines or "horns"; black conical points arranged in a single row, radially on the dorsal side, which may erode and becoming blunt. These dark protrusions are used to scare away possible predators, by looking frightening or dangerous. On the ventral side, tube feet
Tube feet
Tube feet are the many small tubular projections found most famously on the oral face of a sea star's arms, but are characteristic of the water vascular system of the echinoderm phylum which also includes sea urchins, sand dollars and sea cucumbers and many other sea creatures.Tube feet function in...
, purple in color (or pale, transparent pink), are arranged in rows on each arm. Most horned sea stars found are a roughly rigid five-pointed star-shape with tapering arms to the end, although there are anomalies like four or six-armed specimens; they may grow up to 30 centimetres in diameter. The sea stars are usually colored in shades of red or brown, but can be light tan, the color of cookie dough. This appearance, combined with the small horns on its dorsal side, give the sea star a look similar to that of a bumpy cookie. Horned sea stars prefer sheltered, sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
y or slightly mud
Mud
Mud is a mixture of water and some combination of soil, silt, and clay. Ancient mud deposits harden over geological time to form sedimentary rock such as shale or mudstone . When geological deposits of mud are formed in estuaries the resultant layers are termed bay muds...
dy bottoms more than hard substrata such as coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
, and are frequently sighted conspicuously between the leaves of seagrasses on sea grass meadows or on blank stretch of coral sand. In shallow water, this species can be seen intertidally, occasionally exposed to the low tide. they do not withstand rapid changes well, however, and usually keep themselves underwater. In aquariums, these sea stars like to climb around on glass and also filters, which they can disrupt. Sometimes, many individuals of this species can be seen gathering on soft bottom with reason not very well known, probably to increase the chance of fertilization when spawning or simply a suitable feeding ground.
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
s and sponge
Sea sponge
Sponges are animals of the phylum Porifera . Their bodies consist of jelly-like mesohyl sandwiched between two thin layers of cells. While all animals have unspecialized cells that can transform into specialized cells, sponges are unique in having some specialized cells, but can also have...
s in aquarium. In this same setting, they will hunt down snails and eat them. An individual of horned sea star also has been observed eating a sea urchin
Sea urchin
Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...
in their natural habitat. In public aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
s, these stars are sometimes target-fed with chopped squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
s, clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
s or shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
s, and are popular animals for touch pools as it is moderately large in number in some undisturbed areas. Horned sea stars need perfect water condition, suitable diet and proper acclimatization to thrive - thus, these sea stars did not fare very well, caused by several factors mentioned before in many home aquariums. In reef aquariums, they are regarded as undesirable as they have destructive tendencies of toppling decors and digesting patches of corals and sessile organisms; they are reasonably safe if kept in a fish-only aquarium. However, the sea stars are desirable for their cute appearance and relatively non-aggressive behavior.
In many tropical Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
n and Pacific countries, horned sea stars are collected for sea shell trade
Trade
Trade is the transfer of ownership of goods and services from one person or entity to another. Trade is sometimes loosely called commerce or financial transaction or barter. A network that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and...
for their ornate skeletons. In some areas overharvesting is an issue and reduces greatly the population of the echinoderms. Related to this species, the Atlantic Oreaster reticulatus
Oreaster reticulatus
Oreaster reticulatus, commonly known as red cushion sea star, is a species of marine invertebrate, a starfish in the family Oreasteridae.-Description:-Distribution:...
, commonly known as Bahama Sea Star, is also a previously abundant species reduced in number due to the continuous harvesting by the industry and tourists alike.
As with other tropical echinoderms, commensal animals like shrimps (of genus Periclimenes), tiny brittle star
Brittle star
Brittle stars or ophiuroids are echinoderms in the class Ophiuroidea closely related to starfish. They crawl across the seafloor using their flexible arms for locomotion. The ophiuroids generally have five long slender, whip-like arms which may reach up to in length on the largest specimens...
s and even juvenile filefish
Filefish
Filefish are tropical to subtropical tetraodontiform marine fish of the diverse family Monacanthidae. Found in the Atlantic, Pacific and Indian Oceans, the filefish family contains approximately 107 species in 26 genera...
can be found on the surfaces of a horned sea star. This may be attributed to its protective nature, as there are few predators that would dare to eat this echinoderm.