In general, echinoderms have nerve nets and non-centralized nervous systems. Asteroids have optic cushions, or eyespots, and respond to light. Echinoderms in general respond to chemicals, light and touch.
Communication Channels: chemical
Other Communication Modes: pheromones
Perception Channels: visual ; tactile ; chemical
The species is not threatened, but an oil spill at the entrance to Milford Haven in February 1996 spread of 70,000 tons of oil along the Pembrokeshire coast. This location had a major population of Asterina gibbosa which was greatly affected because of the spill. However, observations were made eight weeks after the incident, and there was a good survival of the larger Asterina gibbosa, even some living near small pockets of oil underneath rocks.
US Federal List: no special status
CITES: no special status
Eggs are usually laid on the underside of stones by female Asterina gibbosa. Up to three weeks later, the young hatch bipinnaria and later into brachiolaria larvae. The larvae are bilaterally symmetrical and metamorphose into juveniles.
Development - Life Cycle: metamorphosis
The cushion star does not have any adverse effects on humans.
The cushion star does not have any positive effects on humans.
Cushion stars are omnivorous. As with other starfish A. gibbosa feed themselves by inverting their stomachs in order to digest the food they eat. Their diet includes molluscs, worms and ophiuroids that are also found among rocky shores. They also eat microorganisms, decaying seaweeds and dead invertebrates.
Animal Foods: carrion ; mollusks; aquatic or marine worms; echinoderms; other marine invertebrates
Plant Foods: macroalgae
Other Foods: detritus ; microbes
Primary Diet: carnivore (Eats non-insect arthropods, Molluscivore , Vermivore, Eats other marine invertebrates); omnivore ; detritivore
The cushion star inhabits the regions of Europe's rocky coasts, most commonly the seas to the south and west of the British Isles.
Biogeographic Regions: atlantic ocean (Native )
The cushion star commonly occupies shallow rock pools underneath stones, boulders, and overhangs that provide shelter. Other preferred sites include nestling among algae, sponge masses, or on cliff faces. The cushion star is vertically distributed between the depths of sea level and the intertidal to 130 meters, yet littoral cushion stars are only found in rock pools and relatively damp habitats. This vertical distribution may be extended on shores with rock pools, but this extension will not go beyond the high-water-neap-tide level due to an intolerance to dessication at high temperature, inadequate food supply, and complex behavioral responses to gravity and light. Comparative studies on the ecology of the cushion star at Lough Line showed that A. gibbosa are found in the rocky shallow sub-littoral in varying abundance, yet it was absent from any of the outer shore sites.
Range depth: 130 (high) m.
Habitat Regions: temperate ; saltwater or marine
Aquatic Biomes: temporary pools; coastal
Other Habitat Features: intertidal or littoral
Cushion stars can live up to seven years.
Typical lifespan
Status: wild: 7 (high) years.
Asterina gibbosa is a pentagonal shape with five short arms and a diameter up to 6 cm. The tiny, blunt-armed cushion star ranges in color from greenish-gray, yellowish-green, to reddish-brown. The asteroids are considered a slow moving species with the cushion star being the slowest among all, moving approximately 2.5 cm per minute. The cushion star resembles its given name since the body appears to be inflated like a pillow cushion, emphasizing it small size and blunt arms. The class that the cushion star belongs to, Crinoidea, has retained an upwardly-directed mouth. The cushion star has a body consisting of a tiny central disk to carry the main organs. The mouth of the cushion star is located in the center of the underside. Located on the underside of each arm are grooves that lead to the center that contain hundreds of tube-feet.
Other Physical Features: ectothermic ; heterothermic ; radial symmetry
Starfish are most vulnerable in their larval stage. Few young survive to adulthood.
The cushion star is one of the few sequential hermaphroditic echinoderms. Younger and smaller individuals are males, developing into females as they increase in size and age. Male and female gametes are not readily distinguishable to the naked eye. One would have to see the gonads or see them actually spawning. The gonads on the cushion star are located in each arm. These gonads release the gametes through gonaducts that are located on the central body between the arms. The male gametes are produced first and later only female gametes are produced. Female A. gibbosa deposit up to 1000 eggs in a specific location (usually underside stones) to the ground in the process of reproduction. At the beginning of reproduction, many starfish belonging to the asteroid species form aggregations. In Asterina gibbosa, several males surround or congregate around one female during reproduction.
Range number of offspring: 1000 (high) .
Key Reproductive Features: sequential hermaphrodite (Protandrous ); sexual ; fertilization ; oviparous
There is no post-spawning parental investment.
Parental Investment: pre-fertilization (Provisioning)
Asterina gibbosa, commonly known as the starlet cushion star, is a species of starfish in the family Asterinidae. It is native to the northeastern Atlantic Ocean and the Mediterranean Sea.
Asterina gibbosa is a pentagonal starfish with short blunt arms and an inflated appearance. The aboral (upper) surface is clothed in groups of short, blunt spines. This starfish grows to a diameter of about 5 centimetres (2.0 in) and may be brown, green or orange. It is sometimes blotched with colour and individuals from deeper sea locations tend to be paler in colour. It can be distinguished from the closely related Asterina phylactica by the fact that it has two small spines on each of the plates surrounding its mouth, A. phylactica having no spines on these plates and having a plain olive-green aboral surface with a brown central star.[2] A. gibbosa, at 5 centimetres (2.0 in) is considerably bigger than A. phylactica which seldom exceeds 15 mm (0.6 in). At one time the two were believed to be the same species but it was realised in 1979 that besides the differences in appearance, the two occupied different ecological niches and had different reproductive strategies.[3]
Asterina gibbosa is mainly nocturnal, spending the day underneath boulders, overhangs or in caves, or hidden away under algae in rock pools. It is an opportunistic scavenger but the bulk of its diet comes from the film of bacteria and diatoms that exist on the surface of rocks. It feeds by everting its stomach (turning it inside out) against the surface of the rock and secreting enzymes which digest the film. Other foods found in its stomach included decaying toothed wrack (Fucus serratus), periwinkle faeces and bits of dead molluscs such as mussels (Mytilus edulis), oysters (Ostrea edulis) and periwinkles (Littorina littorea), but 95% of the stomachs contained no large particles indicating the importance in its diet of microscopic organisms.[3]
Asterina gibbosa is a protandric hermaphrodite. This means that it is born a male and later changes sex and becomes a female. Researchers found that at Plymouth, United Kingdom, the sex change happens when it has an arm length somewhere between 9 and 16 millimetres (0.35 and 0.63 in). Other researchers at Naples, Italy found that Mediterranean populations did not have such a clearcut change of sex. In the first year cohort, with arms averaging 11 millimetres (0.43 in), about 80% were male. In the second year batch, with arms averaging 17 millimetres (0.67 in), about 30% were male. By the third year, with 25 millimetres (0.98 in) arms, males were very scarce, but in even larger individuals of unknown age, about 15% were male.[4] Asterina gibbosa may live for six years or more.[5]
The eggs of Asterina gibbosa are laid in a mass and glued to the substrate by their jelly-like coating. Each developing embryo feeds on its egg yolk and hatches directly into a brachiolaria larva, without the intervening mobile planktonic phase of most starfish larvae. The larva has a pair of asymmetric arms which gradually lengthen, and an adhesive disc with which it cements itself to the seabed. It then undergoes metamorphosis, its arms are reabsorbed and tube feet develop and take on the role of anchoring it to the seabed. Later the mouth of the juvenile starfish develops and it is able to start feeding.[6]
Asterina gibbosa is found in the northeastern Atlantic Ocean and the Mediterranean Sea. Its range extends from England, Scotland, Ireland and the southern North Sea southwards to the Mediterranean Sea, Morocco, Tunisia, the Azores, Cape Verde Islands, the Canary Islands and Madeira. It is found from the lower shore down to a depth of about 125 metres (410 ft) in pools, on rocks, under boulders and overhangs.[1]
Asterina gibbosa, commonly known as the starlet cushion star, is a species of starfish in the family Asterinidae. It is native to the northeastern Atlantic Ocean and the Mediterranean Sea.
