In zoology, an ambulacrum is an elongated area of the shell of an echinoderm in which a row of tube feet are arranged. [1] [2] It is pluralized as ambulacra. The area on the shell between ambulacra is known as an interambulacrum.
In zoology, an ambulacrum is an elongated area of the shell of an echinoderm in which a row of tube feet are arranged. [1] [2] It is pluralized as ambulacra. The area on the shell between ambulacra is known as an interambulacrum.
A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal frame to which the organs and soft tissues attach; and the hydroskeleton, a flexible internal structure supported by the hydrostatic pressure of body fluids.
An echinoderm is any animal of the phylum Echinodermata, which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as larvae, as adults echinoderms are recognisable by their usually five-pointed radial symmetry, and are found on the sea bed at every ocean depth from the intertidal zone to the abyssal zone. The phylum contains about 7,600 living species, making it the second-largest group of deuterostomes after the chordates, as well as the largest marine-only phylum. The first definitive echinoderms appeared near the start of the Cambrian.
Vermes ("worms") is an obsolete taxon used by Carl Linnaeus and Jean-Baptiste Lamarck for non-arthropod invertebrate animals.
In neuroanatomy, a plexus is a branching network of vessels or nerves. The vessels may be blood vessels or lymphatic vessels. The nerves are typically axons outside the central nervous system.
Sea cucumbers are echinoderms from the class Holothuroidea. They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. They are found on the sea floor worldwide. The number of known holothurian species worldwide is about 1,786, with the greatest number being in the Asia–Pacific region. Many of these are gathered for human consumption, and some species are cultivated in aquaculture systems. The harvested product is variously referred to as trepang, namako, bêche-de-mer, or balate. Sea cucumbers serve a useful role in the marine ecosystem as they help recycle nutrients, breaking down detritus and other organic matter, after which bacteria can continue the decomposition process.
An endoskeleton is a structural frame (skeleton) on the inside of an animal, overlaid by soft tissues and usually composed of mineralized tissue. Endoskeletons serve as structural support against gravity and mechanical loads, and provide anchoring attachment sites for skeletal muscles to transmit force and allow movements and locomotion.
Blastoids are an extinct type of stemmed echinoderm, often referred to as sea buds. They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississippian subperiod of the Carboniferous period. However, blastoids may have originated in the Cambrian. Blastoids persisted until their extinction at the end of Permian, about 250 million years ago. Although never as diverse as their contemporary relatives, the crinoids, blastoids are common fossils, especially in many Mississippian-age rocks.
Gogia is a genus of primitive eocrinoid blastozoan from the early to middle Cambrian.
Edrioasteroidea is an extinct class of echinoderms. The living animal would have resembled a pentamerously symmetrical disc or cushion. They were obligate encrusters and attached themselves to inorganic or biologic hard substrates. A 507 million years old species, Totiglobus spencensis, is actually the first known echinoderm adapted to live on a hard surface after the soft microbial mats that covered the seafloor were destroyed in the Cambrian substrate revolution.
Eleutherozoa is a subphylum of echinoderms. They are mobile animals with the mouth directed towards the substrate. They usually have a madreporite, tube feet, and moveable spines of some sort. It includes all living echinoderms except for crinoids. The monophyly of Eleutherozoa has been proven sufficiently well to be considered "uncontroversial."
engrailed is a homeodomain transcription factor involved in many aspects of multicellular development. First known for its role in arthropod embryological development, working in consort with the Hox genes, engrailed has been found to be important in other areas of development. It has been identified in many bilaterians, including the arthropods, vertebrates, echinoderms, molluscs, nematodes, brachiopods, and polychaetes. It acts as a "selector" gene, conferring a specific identity to defined areas of the body, and co-ordinating the expression of downstream genes.
Ambulacral is a term typically used in the context of anatomical parts of the phylum Echinodermata or class Asteroidea and Edrioasteroidea. Echinoderms can have ambulacral parts that include ossicles, plates, spines, and suckers. For example, sea stars or "star fish" have an ambulacral groove on their oral side (underside). This ambulacral groove extends from the mouth to the end of each ray or arm. Each groove of each arm in turn has four rows of hollow tube feet that can be extended or withdrawn. Opposite the ambulacral groove is an ambulacral ridge on the aboral side of each ray, known as an ambulacrum. These have interambulacra between them.
The Eocrinoidea were an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, brachiole-bearing echinoderms, and were the most common echinoderms during the Cambrian.
Culcita novaeguineae is a species of starfish. It has short arms and an inflated appearance and resembles a pentagonal pincushion. It is variable in colour and can be found in tropical warm waters in the Indo-Pacific.
Supreme Court Gardens is a park in the central business district of Perth, Western Australia, bounded by Riverside Drive, Barrack Street, Governors Avenue, and the buildings of the Supreme Court of Western Australia.
Camptostroma roddyi is an extinct echinoderm from the Bonnia-Olenellus Zone of the Early Cambrian Kinzers Formation near York and Lancaster, Southeastern Pennsylvania. It is the only known species in the genus Camptostroma, as other species referred to this genus "do not appear to be cogeneric."
The Florida Middle Grounds are a reefs in the northeastern Gulf of Mexico, approximately 128 kilometres west northwest of the West coast of Florida.
Abatus cordatus is a species of sea urchin in the family Schizasteridae. It is native to shallow seas surrounding certain island groups in the southern Indian Ocean. The body is protected by a hard test or shell which is covered with spines. The female broods its young in deep pockets on the upper surface, retaining the young in place with specialised spines. American zoologist Addison Emery Verrill first scientifically described A. cordatus in 1876.
Schizasteridae is a family of echinoderms belonging to the order Spatangoida.
Andrew Benjamin Smith is a British palaeontologist, known for his research on the palaeontology of echinoderms. His cladistic classification of the phylum Echinodermata has become standard.
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