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Species
Asteroidea
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NCBI
EOL Text
Since most all asteroids are marine, they are osmoconformers. There is probably some ionic regulation, but very little. Outpockets of the body wall, called papulae, function in gas exchange and waste excretion. Coelomocytes, specialized cells, accumulate waste and are then released at the distal ends of the papulae.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | ©1995-2013, The Regents of the University of Michigan and its licensors |
Source | http://animaldiversity.ummz.umich.edu/accounts/Asteroidea/ |
Asteroidea is prey of:
Actinopterygii
Cheloniidae
Decapoda
Stomatopoda
Anomura
Asteroidea
Echinoidea
Based on studies in:
Puerto Rico, Puerto Rico-Virgin Islands shelf (Reef)
This list may not be complete but is based on published studies.
License | http://creativecommons.org/licenses/by/3.0/ |
Rights holder/Author | Cynthia Sims Parr, Joel Sachs, SPIRE |
Source | http://spire.umbc.edu/fwc/ |
The Asteroidea is one of the largest and most familiar classes within the Phylum Echinodermata. These animals, commonly known as sea stars or starfishes, form a diverse and speciose group. There are approximately 1600 extant species (Hyman 1955; Clark 1977; Clark and Downey 1992) which are found throughout the world's oceans. Following the classification of Blake (1987), these species are grouped into seven orders: Brisingida, Forcipulatida, Notomyotida, Paxillosida, Spinulosida, Valvatida and Velatida.
Like other echinoderms, asteroids are important members of many marine benthic communities. They can be voracious predators, having significant impacts on community structure. For example, Paine (1966) used Pisaster ochraceus to illustrate his concept of the role keystone species play in community ecology. The crown-of-thorns starfish, Acanthaster planci, is particularly well-known because it can cause extreme detrimental effects to coral reefs, particularly during population outbreaks (Moran 1988).
Figure 1: Pisaster ochraceus and Acanthaster planci, two asteroids of great ecological significance.
Pisaster image by Sherry Ballard, courtesy CalPhotos, copyright © 1999 California Academy of Sciences. Acanthaster image copyright © Borut Furlan.
The controversial Concentricycloidea (a proposed sixth class of the Echinodermata; Baker et al. 1986, Rowe et al. 1988, Pearse and Pearse 1994) have been diagnosed as unusual asteroids (Smith 1988, Belyaev 1990, Janies and Mooi 1999). Their relationship to other asteroid taxa is not well resolved, but alliances with species from the Velatida and the Forcipulatida have been proposed. The unique morphology of the concentricycloids makes it difficult to assign this group to the recognized asteroid orders and is cited as sufficient distinction for class recognition.
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | Emily Knott, Tree of Life web project |
Source | http://tolweb.org/Asteroidea/19238 |
Asteroidea preys on:
Bivalvia
limpets
Gastropoda
Neoloricata
Decapoda
Asteroidea
Echinoidea
Scaphopoda
Priapula
Polychaeta
Ophiuroidea
Hemichordata
Holothuroidea
Echiuroidea
Sipunculidae
Ectoprocta
Cirripedia
Ascidia
Porifera
Cnidaria
Anthozoa
Pollicipes polymerus
Based on studies in:
USA: Alaska, Aleutian Islands (Coastal)
Puerto Rico, Puerto Rico-Virgin Islands shelf (Reef)
This list may not be complete but is based on published studies.
License | http://creativecommons.org/licenses/by/3.0/ |
Rights holder/Author | Cynthia Sims Parr, Joel Sachs, SPIRE |
Source | http://spire.umbc.edu/fwc/ |
The non-centralized nervous system allows echinoderms to sense their environment from all sides. Sensory cells on the epidermis sense light, contact, chemicals and water currents. Higher densities of sensory cells are found in the tube feet and along feeding canal margins.
Red pigmented eye spots are found on the end of each arm. These function as photoreceptors and are clusters of pigment-cup occelli.
Adult pheromones may attract larvae, which tend to settle near conspecific adults. Metamorphosis in some species is triggered by adult pheromones.
Communication Channels: chemical
Other Communication Modes: pheromones
Perception Channels: ultraviolet; tactile ; chemical
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | ©1995-2013, The Regents of the University of Michigan and its licensors |
Source | http://animaldiversity.ummz.umich.edu/accounts/Asteroidea/ |
recent & fossil
License | http://creativecommons.org/licenses/by/4.0/ |
Rights holder/Author | This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License |
Source | http://www.marinespecies.org/aphia.php?p=taxdetails&id=123080 |
Starfishes are equipped with tube feet, and breath through structures known as papillae, tiny structures that are spread across the surface of the body. Oxygen from the water is absorbed by these structures, and by fluid in the main body cavity. Excretion of nitrogenous waste is also done through the papillae. A starfish's body fluid contains phagocytic cells known as coelomocytes, which surround waste material and forcefully eject it into the surrounding water.
License | http://creativecommons.org/licenses/by/3.0/ |
Rights holder/Author | Tom Brodowski, Tom Brodowski |
Source | No source database. |
There are approximately 1500 extant species in the Asteroidea.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | ©1995-2013, The Regents of the University of Michigan and its licensors |
Source | http://animaldiversity.ummz.umich.edu/accounts/Asteroidea/ |
Asteroids are deuterostomes. Fertilized eggs develop into bilaterally symmetrical planktonic larvae, which have 3-part paired coeloms. Embryonic coelomic structures have specific fates as the bilaterally symmetrical larvae metamorphose into radially symmetric adults. Adult pheromones may attract larvae, which tend to settle near conspecific adults. Metamorphosis in some species is triggered by adult pheromones. After settling, the larvae go through a sessile stage and metamorphose.
Development - Life Cycle: metamorphosis
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | ©1995-2013, The Regents of the University of Michigan and its licensors |
Source | http://animaldiversity.ummz.umich.edu/accounts/Asteroidea/ |
A survey of asteroid nomenclature arranged by order has been compiled. Clark (1989, 1993, 1996) and Clark and Mah (2001) list accepted names as well as synonyms, otherwise invalid names, references and ranges of type localities.
Brisingida—Brisingids are deep-sea dwelling asteroids. They usually have many (6-16) long, attenuated arms which are used in suspension feeding. The Brisingida contains about 100 species in 17 genera and 6 families. A preliminary phylogeny for this order has been produced by Mah (1998).
Forcipulatida—These asteroids are distinguished by their forcipulate pedicellariae, which are generally quite conspicuous on the body surface. The Forcipulatida contains about 300 species in 68 genera and 6 families. A preliminary phylogeny for this order has been produced by Mah (2000).
Notomyotida—These are deep-sea dwelling asteroids having flexible arms with characteristic longitudinal muscle bands along the inner dorsolateral surface. The Notomyotida contains about 75 species in 12 genera and 1 family.
Paxillosida—These asteroids are considered to be somewhat infaunal in that they can bury themselves partially under sandy sediments. They are characterized by some morphological features (e.g. pointed, unsuckered tubefeet) which have been considered primitive by some (see Discussion of Phylogenetic Relationships, below). The Paxillosida contains about 255 species in 46 genera and 5 families.
Spinulosida—These asteroids have a relatively delicate skeletal arrangement and completely lack pedicellariae. No fossil spinulosids have been found. The Spinulosida contains about 120 species in 9 genera and 1 family.
Valvatida—These asteroids are quite diverse, but are often characterized by their conspicuous marginal ossicles. Definition of this group has been the most variable and the ordinal definition of many families included here has been controversial (see Discussion of Phylogenetic Relationships, below). The Valvatida contains about 695 species in 165 genera and 14 families.
Velatida—These asteroids typically have thick bodies with large discs and interradial depressions. Contrary to Blake's (1987) classification, molecular evidence suggests a relationship between some velatid and valvatid families (see Discussion of Phylogenetic Relationships, below). The Velatida contains about 200 species in 25 genera and 5 families.
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | Emily Knott, Tree of Life web project |
Source | http://tolweb.org/Asteroidea/19238 |