Echinoderm | Definition, Characteristics, Species, & Facts | Britannica
Nov 14, 2024 · Although all living echinoderms have a pentamerous (five-part) radial symmetry, an internal skeleton, and a water-vascular system derived from the coelom (central cavity), their general appearance ranges from that of the stemmed, flowerlike sea lilies, to the wormlike, burrowing sea cucumbers, to the heavily armoured intertidal starfish or sea ...
Echinoderm - Radial Symmetry, Tube Feet, Spines | Britannica
Nov 14, 2024 · Living echinoderms have a conspicuous five-rayed, radial symmetry that masks their fundamental bilateral symmetry. The skeleton is dermal and each skeletal unit consists of a living tissue (stroma) and a complex lattice (stereom) of calcite.
Echinoderm - Evolution, Adaptations, Paleontology | Britannica
Nov 14, 2024 · echinoderms. Because the phylum Echinodermata was already well diversified by the Lower Cambrian Period, a considerable amount of Precambrian evolution must have taken place. A Precambrian fossil from Australia has triradiate symmetry and a superficial resemblance to an edrioasteroid; it has been suggested that the triradiate condition may have ...
Echinoderm - Radial Symmetry, Tube Feet, Water Vascular System …
Nov 14, 2024 · Echinoderm - Radial Symmetry, Tube Feet, Water Vascular System: The water vascular system is characteristic of echinoderms. Most have cilia on their outer body wall and a coelom modified to form several specialized regions.
Species and distribution of echinoderms | Britannica
echinoderm , Any of various marine invertebrates (phylum Echinodermata) characterized by a hard spiny covering, a calcite skeleton, and five-rayed radial body symmetry.
Echinoderm - Asexual Reproduction | Britannica
Nov 14, 2024 · The gastrula develops into a basic larval type called a dipleurula larva, characterized by bilateral symmetry; hence the name, which means “little two sides.” A single band of hairlike projections, or cilia, is found on each …
Echinoderm - Marine, Invertebrate, Diversity | Britannica
Nov 14, 2024 · Echinoderm - Marine, Invertebrate, Diversity: Diverse echinoderm faunas are found in all marine waters worldwide except the Arctic, where few species occur. When present in large numbers, they can have either a positive or devastating effect on an ecosystem.
Echinoderm - Locomotion, Tube Feet, Water Vascular System
Nov 14, 2024 · Echinoderm - Locomotion, Tube Feet, Water Vascular System: Echinoderm locomotion includes the use of spines, tube feet, and arms; when overturned, they exhibit a righting response. Exclusively marine animals, they occupy a variety of habitats, including using other animals as homes; many burrow in rock or soft sediments.
Echinoderm - Adaptations, Diversity, Characteristics | Britannica
Nov 14, 2024 · Echinoderm - Adaptations, Diversity, Characteristics: Some scientists believe that the higher classification of the echinoderms should be based upon a study of the embryology and anatomy of living groups. Other scientists regard the fossils as …
List of echinoderms | Sea Stars, Sea Urchins, Sea Cucumbers
An echinoderm is any of a variety of invertebrate marine animals belonging to the phylum Echinodermata, characterized by a hard spiny covering or skin. This is a list of significant echinoderms grouped by subphylum and ordered alphabetically followed by a list of extinct echinoderms grouped.