Echinodermata

Echinoderms (Phylum Echinodermata) are a diverse, exclusively marine group of invertebrates that consists of over 13,000 extinct species (15 classes) and 7,000 extant described species within five classes (Asteroidea, Echinoidea, Holothuroidea, Ophiuroidea and Crinoidea).

From: Advances in Marine Biology , 2011

Comparative Reproduction

Gary 1000. Wessel , in Encyclopedia of Reproduction (2nd Edition), 2018

What Are Echinoderms?

The phylum Echinodermata is comprised of five taxa (classes) of organisms with overlapping, withal various, characteristics. The shared characters include radial symmetry – usually five-fold symmetry – in the adults as well as a body wall skeleton, a water vascular organization used for motility in tube anxiety and food communicable devices (pedicellariae), and mutable connective tissue (MCT). This later character may exist unique to echinoderms in that the extracellular matrix undergoes significant structural changes without the use of muscles. This character for many echinoderms likely participates in the process of oral cavity movement, and autonomy, a common feature of sea stars and brittle stars in which the adult severs an arm to escape a predator. In this process the MCT is likely stimulated to go highly flaccid and rupture by the tension of the arm.

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Invertebrates and Their Utilize past Humans

Colin G. Scanes , in Animals and Human Society, 2018

8.viii Echinoderms and Their Apply by Humans

Echinoderms are used for some niche foods. The global production of body of water urchins and sea cucumber is estimated at 178,000 mt (FAO, 2012).

Phylum: Echinodermata

Class: Holothuroidea (bounding main cucumbers)

Class: Echinoidea (sea urchins)

8.8.ane Sea Cucumbers

Sea cucumbers live on bounding main floors and play an of import role in recycling nutrients. They have an exoskeleton and a unmarried gonad. Not only are bounding main cucumbers harvested only are too grown in aquaculture. Japanese sea cucumber (Stichopus japonicus) has been produced in Nippon and China since, respectively, the eighth and 16th centuries CE (Advert).

8.8.2 Sea Urchins

Bounding main urchins are spherical sedentary marine animals with moveable spines and an exoskeleton; they swallow algae. Ocean urchins (scarlet, black, or purple) are heavily harvested to come across consumer demand for gonads particularly in Japan and France (Fig. 8.5). Sea urchins are harvested for their gonads with a market price of over US$100 per kilogram. The gonads tin be erroneously called roe. The gonads are usually consumed raw as sushi and called uni, with three grades:

Figure viii.v. Edible sea urchin.

 Source: Courtesy University of California–Davis.
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Form A uni, golden or bright yellow color

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Form B uni, less vivid yellowish

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Form C uni, "left overs"

Alternatively, sea urchin gonads are salted, pickled, or made into paste.

There has been a pass up in the yield from capture fishing over the concluding 15 years from 115,000 to about 82,000 mt (Carboni et al., 2012). Along with this has been the increasing interest in production by aquaculture (Carboni et al., 2012; McBride, 2005).

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Ultraviolet Radiation and Echinoderms: By, Present and Future Perspectives

Miles Lamare , ... Kathryn Lister , in Advances in Marine Biology, 2011

1.3 The history of UVR enquiry in echinoderms

Echinoderms have played a pivotal role in our agreement of the function of UVR on marine organisms. Research concerning the effects of UVR on echinoderms dates back to the early 1900s, with the total number of publications reaching ≈65 by 2009.The research can be characterised past 2 primary phases: (ane) a period in the 1950s and 1960s involving laboratory studies on the part of UVR in developmental biology and (ii) during the belatedly 1980s to the nowadays when an appreciation of the ecological importance of UVR and ozone depletion drove an increased number of physiological and field studies (Fig. 4.1). Of the published studies, approximately eighty% are on echinoids, with remaining classes the focus of 14 peer-reviewed studies. Furthermore, within this information set, 75% examine UVR responses in the embryological or larval stages, with lesser attention given to the post-settlement life-history stages.

Figure 4.one. Meta-analysis ((Spider web of Scientific discipline (Thomson Reuters, NY) database search: primal words; Echinoderm* OR sea urchin OR starfish OR body of water star OR echinoid OR sand dollar OR body of water cucumber OR brittlestar OR echinoid OR asteroid OR holothuroid OR ophiuroid OR crinoid OR featherstar AND ultraviolet) of the number of published research papers on UVR in echinoderms. Fig. 4.1 represents the cumulative number of papers from and including the year 1900 through to 2009.

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Essays on Developmental Biological science, Part B

Gary Thousand. Wessel , in Current Topics in Developmental Biological science, 2016

6 Diversity in Mechanisms of Germ Line Germination

Echinodermata has v well-defined clades, Crinoidea (bounding main lilies and feather stars), Ophiuroidea (handbasket stars and brittle stars), Asteroidea (starfishes), Echinoidea (sea urchins, sand dollars, and ocean biscuits), and Holothuroidea (ocean cucumbers). Ocean urchins appear to exist the but clade in this phylum that uses acquired germ line determination mechanisms. All other echinoderms announced instead to specify their germ line late in development, likely necessitating inductive mechanisms. Sea stars have been the nigh intensively studied clade outside of echinoids, and the site of germ line germination appears to be within the posterior enterocoele. This construction buds off the endoderm post-obit gastrulation and becomes progressively well defined by mRNAs of germ line factors (e.g., Vasa, Nanos, Piwi) and the absenteeism of somatic markers (e.g., Blimp). Thus, although less is known about this grouping of animals in general than in the sea urchin, this phylum lends itself well to understanding both the acquired mechanism as seen in flies, roundworms, and fish, as well every bit the anterior mechanism seen in, for instance, mammals. With the many manipulations feasible in sea stars, one may be able to more readily dissect inductive mechanisms for germ line determination and contribute to those studies which instead rely largely on genetic manipulations.

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Development and Phylogeny of the Immune System

Eric C.H. Ho , Jonathan P. Rast , in Encyclopedia of Immunobiology, 2016

Introduction: Echinoderms, a Diverse and Widespread Grouping of Marine Animals

Echinodermata is a phylum of about 7000 living species distributed amid five classes: Echinoidea (sea urchins and sand dollars), Holothuroidea (sea cucumbers), Ophiuroidea (brittle stars), Asteroidea (sea stars), and Crinoidea (feather stars and sea lilies). All extant species exhibit distinctive pentaradial symmetry in the developed stage, although the fossil tape indicates that some primitive echinoderms were bilaterally symmetrical. All echinoderms, both fossil and living, possess an endoskeleton made of calcium carbonate in a distinct structural form called stereom. They have a well-documented fossil record that delineates an ancient evolutionary history tracing back to the lower Cambrian menstruation ( Bottjer et al., 2006). As a member of the deuterostome superphylum, echinoderms, along with several smaller groups, are a sister group to the chordates (Effigy 1).

Figure 1. Phylogenetic relationships of bilaterian phyla and the echinoderm classes. (a) Echinoderms are closely related to the chordates. Relationships amongst example bilaterian phyla are shown. Phyla names are shown in black text. The superphylum Deuterostomia (indicated by the dashed line) is comprised of four phyla: chordates, echinoderms, hemichordates, and Xenacoelomorpha. Mammals are members of the jawed vertebrates. Protostomes (indicated by the dotted line) are divided into the Lophotrochozoan and Ecdysozoan subgroups. Instance phyla are indicated (i.e., arthropods and nematodes are ecdysozoans) within each group, although many more phyla are present (the total number of phyla is indicated in gray). (b) Echinodermata is comprised of 5 classes. Although the evolutionary relationships amidst the classes remain somewhat unresolved, current molecular show supports the human relationship shown.

Echinoderms live in marine environments that range from the shallow estuarine to the deep sea in tropical to polar latitudes and oftentimes play integral roles within the marine ecosystem. As adults, echinoderms are predominantly benthic animals although a few species tin can swim. Echinoderms are mostly dioecious and primitively develop indirectly through a planktonic, free-swimming, feeding larval phase that lasts from a few days to many months earlier metamorphosis into a juvenile form (McClay, 2011). However, development in some species is more than directly through a nonfeeding or facultative feeding larval phase (Wray and Raff, 1989). Life span varies significantly betwixt species, ranging from a few years to more than than 200   years (Ebert, 2008). This all-encompassing variation in life history is likely accompanied by a similarly heterogeneous suite of immune mechanisms inside this phylum.

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Echinoderm Responses to Variation in Salinity

Michael P. Russell , in Advances in Marine Biological science, 2013

Abstruse

Although Echinodermata is one of the only stenohaline phyla in the animal kingdom, several species evidence remarkable abilities to acclimatize and survive in euryhaline habitats. The last comprehensive review of this topic was over 25 years ago and much work has been published since. These recent studies expand the field reports of species living in hyposaline environments and detail experimental research on the responses, physiological range, and limits of echinoderms to salinity challenges. I provide a brief review of the historical concepts and measures of salinity and relate this overview to the physiological and ecological studies on echinoderms. Many marine biologists are non aware that chemic oceanographers advocate abandoning today's ordinarily used measure of salinity, 'PSU', in favour of accented salinity (SA )—a return to the ppt (‰) metric. The literature survey reveals only ane euryhaline-tolerant species in the Southern Hemisphere (there are 42 in the North) and more than euryhaline species in the geologically older, brackish seas. The light-green sea urchin, Strongylocentrotus droebachiensis, is one of the nearly tolerant echinoids to hyposalinity. Different source populations have varying levels of acclimation and tolerance to hyposalinity. Experiments bear witness that greenish urchins previously unexposed to hyposalinity experience a clear subtract in growth rates; all the same, this adverse effect is curt lived. Light-green urchins already acclimated to hyposalinity tin suffer intense and repeated bouts and grow at the same rate of urchins not exposed. Promising hereafter work on the physiological and cellular mechanisms of hyposalinity acclimation includes comparative studies of the role of heat shock proteins in the response to changing salinities.

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Deuterostomes and Chordates

Noriyuki Satoh , in Chordate Origins and Evolution, 2016

1.iii.1 Echinoderms

The Phylum Echinodermata (Greek echinos, "spiny"; derma, "skin") contains approximately 7000 living species with five singled-out classes, including the Crinoidea (sea lilies and feather stars), Asteroidea (sea stars), Ophiuroidea (brittle stars), Echinoidea (sea urchins and sand dollars), and Holothuroidea (bounding main cucumbers; Fig. 1.2A). In improver, in that location are approximately 13,000 fossil species (Chapter three).

Effigy 1.two. Echinoderms.

(A) Five extant classes of echinoderms: from left to right, crinoids (sea lilies), asteroids (sea stars), ophiuroids (breakable stars), holothuroids (sea cucumbers), and echinoids (sea urchins) (upper panels). All echinoderm adults are pentaradially symmetrical, a considerable modification of the ancestral bilaterian trunk plan. However, their larvae are bilaterally symmetric (lower panels). Phylogenetic relationships of the five classes are shown at the lesser. (From Lowe, C.J., Clarke, D.North., Medeiros, D.Yard., Rokhsar, D.S., Gerhart, J., 2015. The deuterostome context of chordate origins. Nature 520, 456–465.) (B) Echinoderms are characterized by a conserved body programme, most clearly represented by the Asteroidea. Here a diagram of an asteroid with cutaways to show internal beefcake illustrates the major features, including the mesoderm-derived h2o vascular system, a hydraulic system that drives the distinctive tube feet used for feeding and locomotion, five radial fretfulness that run along each arm/ambulacrum linked by a nervus ring, and the mesoderm-derived skeleton. (From Lowe, C.J., Clarke, D.N., Medeiros, D.M., Rokhsar, D.S., Gerhart, J., 2015. The deuterostome context of chordate origins. Nature 520, 456–465.) (C) Embryogenesis and larvae of the crown-of-thorns starfish, Acanthaster planci. (a) Fertilized egg, (b) four-jail cell embryo, (c) blastula, (d) early gastrula, (e, e′) late gastrula, (e) front view and (e′) side view, (f, f′) bipinnaria larva, (f) front view and (f′) side view, and (thousand) brachiolaria larva, front view. (Courtesy of Keita Ikegami.)

Echinoderms are benthic, marine organisms that constitute one of the best-defined animate being phyla. Offset, adult echinoderms are the only animals with pentameric, radial symmetry (Fig. 1.2A, upper), although their larvae are bilateral (Fig. 1.2A, lower). Second, they possess a unique calcareous endoskeleton arising from mesodermal tissue and composed of split up plates or ossicles. Each plate originates equally a single mesh-like structure called a stereo, the interstices of which are filled with living tissue (stroma). Third, their left mesocoel (hydrocoel) constitutes a h2o vascular organization composed of a complex serial of fluid-filled canals, usually evident externally as muscular podia. In addition, echinoderms contain unusual types of connective tissue, the stiffness of which is modulated past neuropeptides (Birenheide et al., 1998; Santos et al., 2005).

Prosomes, mesosomes, and metasomes are unrecognizable externally, simply the development of compartments from coelomic pouches of bilateral larvae clearly reveals a body organization with three singled-out coelomic cavities: protocoel, mesocoel, and metacoel (called archimery). The nervous organisation is non centralized and usually consists of a nerve net and radial nerves. The lack of a encephalon-like structure results in a nervous system that is complicated and unusual. There are ring fretfulness around the esophagus and radial nerves along the ambulacra (Fig. one.2B). These nervous systems possess an ectodermal (ectoneural) nerve and a mesodermal (hyponeural) nerve separated by a basement membrane. The onetime is mainly sensory whereas the latter is motor. Gonads are formed from mesodermal elements of the metacoel. Gap junctions have non been observed in any species. Echinoderms lack excretory organs. Circulation depends upon a hemal arrangement derived from coelomic cavities and sinuses.

Most echinoderms are dioecious, and evolution is usually indirect. Their embryology is fundamentally deuterostomous, with radial cleavage, a hollow blastula, gastrulation past invagination of endodermal cells, endodermally derived mesoderm, enterocoely, and a blastopore that forms the anus (Fig. 1.2C; Wray, 1997; Davidson, 2006; McClay, 2011). The digestive system is complete, only it has get secondarily incomplete or lost in some species.

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Taxonomy and Identification

Huan Zhao , in Developments in Aquaculture and Fisheries Scientific discipline, 2015

Summary

Ocean cucumbers (Echinodermata: Holothuroidea), also ordinarily called holothurians or holothuroids, accept traditionally been classified through their morphological phenotype, particularly the analysis of their anatomy, including tentacles, papillae, and ossicles (infinitesimal calcareous elements). Present, traditional approaches are being complemented by molecular techniques applied to systematics and taxonomy. In the present chapter, we talk over the identification and taxonomy of holothuroids with specific references to Apostichopus japonicus. Nosotros also describe morphological variability (e.g., color and shape) in A. japonicus that complicates the identification of live specimens and dried processed products (beche-de-mer).

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Methods in Cell Biology

Kazuo Inaba , Katsutoshi Mizuno , in Methods in Cell Biology, 2009

A Sea Urchins

Sea urchins (Echinodermata) accept been used in the report of gametes and fertilization for a long time. Large amounts of sperm can exist nerveless. Gametes are artificially spawned past injection of 0.5  K KCl or 100   mM acetylcholine into the body cavity (Fig. 1A). Alternatively, information technology can be placed in the trunk cavity after removal of the mouthparts (Aristotle's lantern), but injection by syringe needle is highly recommended because it does non kill the animals and they tin can survive the collection of gametes (Fig. 1A). Later on injection, the males are put on a large Petri dish or tray with the gonopores facing down (Fig. 2A). After half an 60 minutes, the sperm attached to the torso surface near the gonopore are isolated past washing with seawater and the urchin is removed. Although the volume of sperm depends on species, 0.5–2   ml of dry sperm (undiluted sperm) can exist usually obtained from ane male person.

Fig. 1. Drove of sperm. (A) Injection of acetylcholine using a syringe into the body cavity of a bounding main urchin. (B) Collection of sperm from the sperm duct of Ciona. Subsequently opening the tunic and torso wall, the creature is held with tissue newspaper. Sperm are collected using a micropipette with a tip after piercing the sperm duct with a needle. (C) Drove of sperm from the whiting Sillago japonica. Sperm are squeezed out of the cloaca and collected using a micropipette with a tip.

Fig. two. (A) Multiple sea urchins are put in a large petri dish after injection of acetylcholine. Sperm are so recovered by a pipette. (B) Homogenization of sperm in a glass/Teflon Potter–Elvehjem-type homogenizer on ice. The homogenizer is connected to a motor-drive unit.

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Teeth: Construction/Mechanical Design Strategies

S. Weiner , P. Zaslansky , in Encyclopedia of Materials: Scientific discipline and Technology, 2004

1 Sea Urchin Teeth

Sea urchins (phylum Echinodermata) produce five continuously growing teeth ( Fig. 1(a)) that are used for grinding the rocky substrate in order to extract the algae that tightly attach to the surface. In fact, some of the rock itself is ground abroad. Amazingly, the molar is composed of basically the aforementioned textile every bit the stone that they ordinarily grind, namely calcium carbonate. The tooth structure and modifications of the mineral stage are what makes it possible to grind away the rocky substrate. The molar is continuously renewed as the scraping surface is worn downwards, and is self-sharpening (Fig. 1(a)) (Hyman 1955). For more than data on the overall tooth structure come across Markel et al. (1977) and Stock et al. (2002). Here we will consider simply a few of the structural features.

Figure 1. SEM of a sea urchin (Paracentrotus lividus) tooth. (a) The working tip of the whole tooth showing the self-sharpening profile. (b) The working tip showing the core equanimous of calcite needles embedded in a matrix of high-Mg calcite crystals. The core is surrounded by plates. (c) A crystal fiber that tapers in size from i end to the other. The thin end is embedded in the working tip. Micrographs are adapted from those in Wang et al. (1997).

The basic structural elements of the tooth are long S-shaped fibers each of which is a single crystal of calcite. Each fiber is enveloped in an organic sheath. The fibers taper from 20   μm in diameter in the keel area to less than 1   μm or then in the working surface (Fig. ii(c)). There is also a reduction in the magnesium content from the keel side to the working surface (Wang et al. 1997). The reduction in size results in the hardness of the element increasing due to the decrease in the number of possible dislocations. The working surface (Fig. two(b)) is composed of the tips of the fibers emerging perpendicular to the surface. Each fiber is embedded in a matrix of rounded and somewhat disordered crystals of disk-shaped calcite that comprise very large amounts (up to 35   mol.%) of magnesium within its lattice. The 2 phases are separated by an organic sheath (Wang et al. 1997). Resistance to fracture is presumably derived from the juxtaposition of the hard needles in a matrix of small rounded crystals. Furthermore, movement between the two can occur along the interface. In certain respects the tooth tin can exist regarded equally a gradient fiber-reinforced composite textile in which both the fibers and the matrix are composed of mineral. For more than information on structure and other blueprint strategies built into the tooth structure, including the self-sharpening belongings, see (Wang et al. 1997).

Effigy 2. Micrographs of the teeth of the limpet Lottia sp. (a) SEM of a mineralized tooth. (b) SEM of the hard outer working layer containing goethite in an organic matrix. (c) SEM of the softer inner layer containing opal in an organic matrix. Micrographs are from the collection of the late Prof. Heinz A. Lowenstam.

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