Echinoderm

A further unique echinoderm graphic symbol, nigh certainly nowadays in fossil taxa, is catch connective tissue, which is a type of ligament that tin alter its properties from pliable to rigid, enabling parts of the skeleton, such as the stem or arms, to 'lock' into position for prolonged periods with minimal energy expenditure.

From: Encyclopedia of Geology , 2005

FOSSIL INVERTEBRATES | Echinoderms (Other Than Echinoids)

A.B. Smith , in Encyclopedia of Geology, 2005

Phylogenetic Relationships

Echinoderms are triploblastic Metazoa, which, despite their unique pentaradiate adult trunk plan, vest to the Bilateria. More specifically, echinoderms are members of the group Deuterostoma, i.due east. bilaterians in which the embryonic blastopore develops into the anus rather than the rima oris. This aligns echinoderms with chordates and hemichordates, the latter comprising acorn worms, pterobranchs, and the extinct graptolites ( see FOSSIL INVERTEBRATES | Graptolites). Contempo molecular and morphological analyses unambiguously betoken that echinoderms and hemichordates are the more than closely related, and together these course the taxon Ambulararia. Both hemichordates and echinoderms have a vascular system of tubes (the water vascular organisation of echinoderms and the tentacular system of pterobranchs) that originates from the homologous primary body coeloms. In hemichordates the tentacular system is symmetrically paired and forms from both the left and the right mesocoel. In echinoderms simply the left mesocoel forms the water vascular system, and hence there is only a unmarried hydropore. Equally both hemichordates and chordates are bilaterally symmetrical as adults and comport gill slits (pharyngeal openings), the latest common ancestor of echinoderms and hemichordates must also have been bilaterally symmetrical and have possessed gill slits.

Echinodermata are divided into 5 extant classes, which together form the crown group of the phylum. These are the Crinoidea (plume stars and sea lilies) (see FOSSIL INVERTEBRATES | Crinoids), Asteroidea (starfishes), Ophiuroidea (brittle stars), Echinoidea (sea urchins) (meet FOSSIL INVERTEBRATES | Echinoids) and Holothuroidea (sea cucumbers). Major differences carve up the body plan of crinoids from those characterizing the other 4 classes, and molecular and comparative data all signal to crinoids equally the most primitive of the extant echinoderm classes. The crinoids and their extinct stalked relatives the blastozoans together class the group Pelmatozoa. Asteroidea, Ophiuroidea, and the Echinozoa form a sister clade, the Eleutherozoa, and are free-living. Molecular evidence suggests that amongst eleutherozoans the Echinoidea and Holothuroidea are the most closely related, and together they course the group Echinozoa. Echinozoa have a globular to cylindrical trunk grade with the aboral surface highly reduced. Past dissimilarity, asteroids and ophiuroids have a stellate body plan and their oral and aboral surfaces are equally adult. The extinct edrioasteroids are an important early on eleutherozoan group.

In that location are some numerically small but interesting stalk-group echinoderms; most of import amid these are the carpoids (see below). Carpoids all lack pentaradiate symmetry, and most lack an ambulacral organization while retaining pharyngeal gill slits.

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Sandy-Beach Invertebrates

Anton McLachlan , Omar Defeo , in The Ecology of Sandy Shores (Third Edition), 2018

Phylum: Echinodermata

Echinoderms are not typical of sandy beaches, although on sheltered shores some, such as the echinoids Echinodiscus and Dendraster, may movement shoreward to the bottom of the intertidal slope. Exceptions are the sand dollars Encope and Mellita, which occur intertidally as well as subtidally. The echinoderm more commonly associated with sandy beaches is, all the same, Echinocardium, which is confined to intertidal and shallow-water sands, usually in sheltered areas simply occasionally in moderately exposed situations. Information technology excavates a semipermanent burrow for itself so that, like other such invertebrates (Arenicola, Callianassa), its intertidal distribution is limited to beaches stable plenty to back up its burrows. The larvae of Echinocardium settle offshore and drift toward the intertidal region every bit they mature, the adults burrowing either in the immediate subtidal or intertidally in the zone of saturation. Echinocardium is cosmopolitan in its distribution. The surf zones of sandy beaches, and particularly the outer turbulent zone, may exist rich in echinoderms, including not just echinoids simply as well holothurians, ophiuroids such every bit Amphiura, Ophiothrix and Paracrocnida, and asteroids such as Asterias and Astropecten, peculiarly in the shallow subtidal region.

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Geologic History and Energy

S.A. Elias , in Encyclopedia of the Anthropocene, 2018

Echinoderms

Echinoderms are a phylum of marine invertebrates that include starfish, brittle stars, sea cucumbers, body of water urchins, sand dollars, and crinoids. They are ane of the well-nigh diverse groups of marine invertebrates and play important ecological roles from the near-shore environment to the deep seas. Dupont et al. (2010) reviewed potential most-futurity body of water acidification effects on echinoderms. Their assay of the literature reveals that echinoderms are surprisingly resistant to the effects of acidification, but they noted important differences in sensitivity between populations and species. The studies they reviewed are almost all based on brusque-term or midterm observations and experiments. As with other calcifiers discussed earlier, long-term investigations of echinoderm sensitivity to bounding main acidification are few and far between. Dupont et al. (2010) noted that individual species' responses to acidification involve physiological processes and that different stages within echinoderm life cycles may exist more than or less sensitive to this stressor. They too observed that interactions between species may play an important role so that ecological processes may plow what would otherwise exist minor-scale, sublethal effects into large-scale impacts in benthic communities.

Brennand et al. (2010) examined the interactive effects of increased ocean temperature and acidification on larval development in the tropical ocean urchin Tripneustes gratilla. They reared larvae under experimental conditions that replicate predicted conditions in the immediate time to come for the coastal waters of southeast Australia. They institute that increased acidity and decreased carbonate mineral saturation significantly reduced larval growth, resulting in decreased skeletal length. Nether increased acidity, in which pH was lowered by 0.3–0.5   pH units, larval calcification was profoundly reduced. Nevertheless, a 3°C warming diminished the negative effects of acidification and elevated CO2 levels in the blood on larval growth. However, the dwarfing furnishings of acidification were dominant. Reduction in size of bounding main urchin larvae in a CO2-enriched ocean would likely impair their operation with negative consistent effects for benthic adult populations.

Dupont et al. (2010) hypothesized that populations/species naturally exposed to variable environmental pH conditions may be preadapted to future ocean acidification, highlighting the importance of understanding and monitoring ecology alter, to facilitate predictions of sensitivity to future ecology impacts. The authors stress that more cross-disciplinary research is needed between ecotoxicology and ecology, to address multiple water quality factors. As discussed before for other calcifiers, bounding main acidification does not act in isolation on echinoderms. Rather, they are beingness exposed to multiple stressors, including increasing ocean temperatures and pollution. Dupont et al. (2010) conclude that the available information indicate that in the firsthand future, body of water acidification will accept negative impacts on echinoderm taxa with probable significant consequences at the ecosystem level.

Another aspect of marine organism wellness is its immune system. As discussed earlier, exposure to sea acidification may make animals more vulnerable to various kinds of stressors. Hernroth et al. (2011) examined the effects of exposure to the level of ocean acidification predicted for the year 2100 (pH 7.vii) on immune and stress responses in adult specimens of the starfish, Asterias rubens. Analyses were made after 1 week and later on 6 months of continuous exposure. Following ane-week exposure to acidified water, the pH of body fluids was significantly reduced. Changes in immunity indicators showed that the starfish's allowed system was depressed by approximately 50%. Post-obit long-term exposure (6 months), immunity was even further dumb. These results suggest quite serious consequences for echinoderm resistance to pathogens in a futurity acidified ocean.

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Marine Ecosystems of Andaman and Nicobar Islands – Species Affluence and Distribution

Nambali Valsalan Vinithkumar , ... Nambali Valsalan Sujathkumar , in Biodiversity and Climate Change Adaptation in Tropical Islands, 2008

4.7 Distribution of Echinoderms

Echinoderms belong to the phylum Echinodermata having five classes namely Crinoidea (Body of water lilies and Feather stars), Ophiuroidea (Brittle stars and basket stars), Asteroidea (Sea stars), Echinoidea (Body of water urchins) and Holothuoidea (Sea cucumbers) ( Fig. 8.11). They are benthic and plant in all depth of the oceans around the world. They are good scavengers in lesser and grazing on various micro and macro algae, corals etc. Some of the members like crown of thorn starfish Acanthaster planci (Linneaus, 1758) known to graze corals in big numbers create local coral bleaching and destruction of coral reefs. Some of the species belong to grade Holothuroidea (sea cucumbers) are used as food as well as medicine. All the five classes of organisms are constitute distributed in Andaman and Nicobar Islands surrounding marine environments (Table 8.4). In full 777 echinoderm species were reported from Republic of india. Many species are establish associated with coral reefs, sea grass meadows and seaweed beds. As per the status and distribution of Echinoderms in reef communities of Nicobar Islands, 75 species belonging to 42 genera, 24 families and 12 orders were reported (Koushik et al., 2013). The Ophiuroid diverseness was reported to be higher in Nancowry Island and minimum in Automobile Nicobar Island. The species of Echinoderm include Holothuria atra, Stichopus chloronotus, Ophiocoma erinaceus, Ophiothris pussila along with Comatula pectinata every bit almost ascendant in Nancowry Islands (Koushik et al., 2013).

Figure 8.11. Sea cucumber – Echinoderm in coral reef environments.

Tabular array viii.4. No of Echinoderm Species Recorded Around the Globe

Sl. No. Grade Global India
1. Crinoidea 620 86
2. Ophiuroidea 1600 180
three. Asteroidea 1600 193
4. Echinoidea 940 130
5. Holothuoidea 1100 188
Total 5860 777

There many commercially important species of echinoderms and the dried organism are sold every bit souvenir. They are known for their delicacy in Southeast Asian countries. Some of the species are known for the bioactive compounds with anti-microbial, anti-inflammatory, anticancer and anti-coagulant. The sea cucumber body wall is sold as beche-de-mer or trepan in Southeast Asian countries; hence about 4000 tonnes are annually collected from coastal ecosystems effectually the world. The over exploitation of the sea cucumber resulted in depletion in the coastal areas of Republic of india. Hence to conserve and protect these organisms, the Ministry of Environment and Forests and Climate change, Government of India strictly banned the collection with a notification on 11th July 2001 declared all species of holothurians under Schedule – I Category of the wild animals (Protection) Act 1972.

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Early on History of Symbiosis in Living Substrates: Trace-Fossil Bear witness from the Marine Tape

Leif Tapanila , A.A. Ekdale , in Trace Fossils, 2007

Crinoids

Echinoderms have hosted symbionts since the Ordovician, and these relationships are especially common in crinoids. Several varieties and arrangements of parabolic pits, called Tremichnus, are described from the columnals and crowns of crinoids (Brett, 1985). Unlike bioclaustrations in most basal skeletons where growth decreases slightly nigh the cavity, the pits in echinodermal plates are often accompanied by increased and swollen skeletal growth. Like bioclaustrations are found in echinoids from the Paleozoic and Mesozoic (east.g., Feldman and Brett, 1998; Neumann, C. personal communication, 2004), and they are currently being investigated.

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Oman

Michel R. Claereboudt , in World Seas: an Environmental Evaluation (2nd Edition), 2019

2.3.9 Echinoderms

The Echinoderm fauna was mainly investigated in the tardily 1980s ( Campbell, 1988) and led to the discovery several owned or regionally endemic species such as F. sadhensis (Marsh & Campbell, 1991), Patiriella paradoxa (Campbell & Rowe, 1997), and several other species await formal description. The ocean cucumber animate being includes at least 25 species (Claereboudt & Al-Rashdi, 2011) with similar richness for starfishes and sea urchins (Campbell, 1988). The crown-of-thorn starfish (Acanthaster planci) is i of the main forcing drivers of coral reefs in the Sultanate (Glynn, 1993) where it constitutes a biological threat to coral communities today (Personal Observations), specially in the Majuscule Surface area and the coral communities in the Daymaniyat Islands.

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The Antecedents of Invertebrate Ichnology in North America: The Canadian and Cincinnati Schools

S. George Pemberton , ... Murray One thousand. Gingras , in Trace Fossils, 2007

Contributions to Ichnology

Although echinoderms were his specialty, he studied and wrote on all invertebrate groups. Over the course of his professional life, he erected lx-one new genera and 1065 new species. His bibliography comprises over 200 titles, a remarkable feat for substantially a self-taught paleontologist. Billings was an early contributor to the field of ichnology in Due north America. He erected three ichnogenera, Saerichnites Billings, 1866; (Arthraria Billings, 1872; and Licrophycus Billings, 1862, and at least seventeen ichnospecies including species of Skolithos (S. canadensis Billings, 1862), Cruziana (C. similis Billings, 1874), Palaeophycus (P. incipiens Billings, 1861a; P. congregatus Billings, 1861a; P. beverleyensis Billings, 1862; P. funiculus Billings, 1862; P. obscurus Billings, 1862; and P. beauharnoisensis Billings, 1862), Rusophycus (R. grenvillensis Billings, 1862), and Eophyton (Due east. jukesi Billings, 1874)). Of these, Saerichnites and Artharia are all the same considered valid, while Licrophycus (Fig. 2.3B) is now grouped with Phycodes. Many of the species tin be incorporated into existing taxa or, as in the case of Eophyton, may represent inorganic structures. Billings' fossil descriptions bespeak that he considered that the fossil remains were those of plants, and not the traces left behind by the activities of an organism. He followed the convention of the day that many of these markings were, in fact, seaweeds.

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Trace Fossils as Indicators of Sedimentary Environments

Shahin Due east. Dashtgard , Murray Thou. Gingras , in Developments in Sedimentology, 2012

2.four Echinoderms

Mobile echinoderms include starfish, breakable stars, irregular and regular echinoids, and sea cucumbers. All these animals are known to go out distinctive traces in modern sediments, although only spatangoid (irregular) echinoids and some groups of sea cucumbers burrow securely into soft substrates ( Fig. 6).

Figure 6. Examples of burrowing echinoderms, cnidarians, and holothurians, and their couch morphologies. Near photos of animals were taken in the Strait of Georgia, Canada. Trace names are assigned based on morphological similarities between the burrows and mutual trace fossils.

 The photos of Brisaster latifrons, Pentamera pseudocalcigera, Leptosynapta clarki, and Molpadia intermedia were provided past Korhan Ayranci. Couch morphology is derived from a variety of sources: B. latifrons from Goldring et al. (2007); E. cordatum from Bromley and Asgaard (1975) and Kanazawa (1992); Pachycerianthus is modeled afterward Schäfer (1972) and Bromley (1996); Utricina from Sanamyan and Sanamyan (2006) and McDonald (2010); P. pseudocalcigera from Howard (1968) and Gingras et al. (2008a); 50. clarki from (Myers, 1977b); and, Yard. intermedia from the authors inquiry and from Schäfer (1972), Rhoads (1974), and Bromley (1996). Living position of Chiliad. intermedia in mud is deduced from ongoing research in the Strait of Georgia, Canada.

Spatangoid echinoids burrow in both sandy and muddy substrates. These animals move through the sediment by passing grains effectually their bodies using their tube feet (Bromley, 1990; Bromley and Asgaard, 1975; Kanazawa, 1992; Nichols, 1959). In muddy sediments, spatangoid echinoids burrow only a few centimeters below the surface. In sand, they burrow deeper, upwardly to 20   cm in the case of Echinocardium cordatum (Fig. vi). The back-filled echinoid tunnels can be broadly classified as Scolicia or Beaconites (Fu and Werner, 2000), although Scolicia should show a preserved axial canal near the eye of the trace fossil (Plaziat and Mahmoudi, 1988; Smith and Crimes, 1983). Interfacial preservation of Scolicia leads to the product of Taphrhelminthopsis, which has recently been observed on submarine videos of the Fraser Delta front, British Columbia, Canada. Sand dollars are too known to tilt into the sediment (in the same mode as brittle stars), such that part of their torso is buried and function extends above the sediment/water interface (O'Neill, 1978). This behavior is likely to produce small chevron-shaped disruptions that reflect the orientation of the breakable stars and sand dollars.

Sea cucumbers probably produce a broader range of trace fossils than are soon ascribed to them in the ichnological literature. They are observed to make rough, sinuous trails at the sediment/h2o interface and are known to make large, if crude, bow-shaped Arenicolites and Diplocraterion in intertidal settings (Howard, 1968; Pearse, 1908). In deeper water settings, sea cucumbers produce Arenicolites, Skolithos (Bromley, 1996; Heezen and Hollister, 1971; Myers, 1977a,b; Rhoads, 1974; Rhoads and Young, 1971; Schäfer, 1972), and concentrically laminated, Asterosoma-similar and spreitenated, Teichnichnus-like traces (Fig. 6; Ginsburg et al., 1966; Zhang et al., 2008). Arenicolites and Diplocraterion-like traces are produced by break-feeding holothurians, whereas traces similar to Skolithos, Asterosoma, and Teichnichnus are made past holothurians employing deposit-feeding strategies. Recognition of holothurian-generated burrows requires additional research; our present understanding of the burrows fabricated by these animals is limited and does not enable recognition of the paleo-infaunal community.

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Sea Urchins: Biological science and Ecology

J.R.M.C. Silva , in Developments in Aquaculture and Fisheries Science, 2013

1.three Phagocytosis

Phagocytosis by echinoderm coelomocytes was first observed in the perivisceral coelom of Asterias rubens by Durham in 1891 (in V. J. Smith, 1981, p. 532) after injection of India ink or blueish aniline. Phagocytic amoebocytes were also institute in the tube feet, gut wall, and other organs by Cuénot in 1891 (in V. G. Smith, 1981, p. 532). Since and then, numerous studies have reported the coelomocytes of many species of echinoderms taking upward various substances, including leaner, inert particles, foreign cells, and senescent cells (Cuénot, 1948; Millott, 1950; Boolootian and Giese, 1958; Johnson and Beeson, 1966; Johnson, 1969c; Hobaus, 1978; Silva, 2000). Among echinoderms, the uptake of particles seems to take place but by amoebocytes (Johnson, 1969c; Bertheussen and Seljelid, 1978; Five. J. Smith, 1981; Isaeva and Korenbaun, 1990; Edds, 1993; Chia and Xing, 1996; Mangiaterra and Silva, 2001; Silva et al., 2001), and simply past the petaloid form of this prison cell type (Boolootian and Giese, 1958; Johnson, 1969a, c; 5. J. Smith, 1981). The amoebocytes are also the only coelomocytes containing intranuclear atomic number 26 bodies (Vevers, 1967; Millott and Vevers, 1968; Johnson, 1969b; Hobaus, 1978), which can exist considered a typical feature of these cells. Hydrogen peroxide product past sea urchin phagocytes has been described only in Strongylocentrotus nudus in vitro (Ito et al., 1992). Phagocytosis of erythrocytes by phagocytes is enhanced by opsonization with the coelomic fluid of S. nudus. Phagocytes during the stimulated state produce more hydrogen peroxide than resting phagocytes; however, hydrogen peroxide production by phagocytes is non affected by the osponic activity of the coelomic fluid (Gross et al., 1999). Some authors subdivide the population of phagocytic amoebocytes into discoidal cells, polygonal cells, and small phagocytes (Smith, 1981).

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Sea Urchins: Biological science and Ecology

José Roberto Machado Cunha da Silva , in Developments in Aquaculture and Fisheries Science, 2020

1.three Phagocytosis

Phagocytosis by echinoderm coelomocytes was outset observed in the perivisceral coelom of the asteroid Asterias rubens past Durham in 1891 afterward the injection of India ink or blue aniline. PAs were too found in the tube feet, gut wall, and other organs by Cuénot in 1891 (Smith, 1981, p. 532). Since then, numerous studies have reported coelomocytes of many species of echinoderms taking up various substances, including leaner, inert particles, strange cells, and senescent cells (Cuénot, 1948; Boolootian and Giese, 1958; Johnson and Beeson, 1966; Millott and Vevers, 1968; Johnson, 1969c; Hobaus, 1978; Silva, 2000). Amid echinoderms, the uptake of particles seems to take place simply by amoebocytes (Johnson, 1969c; Bertheussen and Seljelid, 1978; Smith, 1981; Isaeva and Korenbaun, 1990; Edds, 1993; Plytycz and Seljelid, 1993; Chia and Xing, 1996; Mangiaterra and Silva, 2001; Pinsino and Matranga, 2015; Marques-Santos et al., 2018), and only by the petaloid form of this cell type (Boolootian and Giese, 1958; Johnson, 1969a,c; Smith, 1981). The amoebocytes are also the only coelomocytes containing intranuclear atomic number 26 bodies (Vevers, 1967; Millott and Vevers, 1968; Johnson, 1969b; Hobaus, 1978), which tin exist considered a typical feature of these cells. Hydrogen peroxide production by sea urchin phagocytes has been described only in Mesocentrotus (as Strongylocentrotus) nudus in vitro (Ito et al., 1992). Phagocytosis of erythrocytes by phagocytes is enhanced past opsonization with the coelomic fluid of M. nudus. Phagocytes during the stimulated state produce more hydrogen peroxide than resting phagocytes. However, hydrogen peroxide production by phagocytes is not affected by opsonic activity of the coelomic fluid (Gross et al., 1999). Some authors have subdivided the population of PAs into discoidal cells, polygonal cells, and small-scale phagocytes (Smith, 1981) (Fig. 13.iii).

Fig. 13.3

Fig. xiii.3. Lytechinus variegatus phagocytic amoebocytes incubated with yeast for 1   h (calibration bar   =   10   μm). Scanning electron microscopy of phagocytic amoebocyte incubated with yeast for 4   h.

 Figure from Dr. João Carlos Shimada Borges, with permission.

In an attempt to explain why Diadema antillarum underwent mass mortality in the Caribbean while sympatric species did not, Beck et al. (2014) studied the humoral response of D. antillarum, Echinometra lucunter, and Tripneustes ventricosus to lipopolysaccharides (LPS), a component of Gram-negative bacteria. They have reported that the response was absent in D. antillarum but not in the other species. Yet, no differences in cellular phagocytic response compared with other sea urchin species were noted by DeFilippo et al. (2018).

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