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Sand Dollar
Sand dollars (also known as a sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) are species of flat, burrowing sea urchins belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are known as '' sea biscuits''. Sand dollars can also be called "sand cakes" or "cake urchins". Anatomy Sand dollars are small in size, averaging from three to four inches. As with all members of the order Clypeasteroida, they possess a rigid skeleton called a test. The test consists of calcium carbonate plates arranged in a fivefold symmetric pattern. The test of certain species of sand dollar have slits called lunules that can help the animal stay embedded in the sand to stop it from being swept away by an ocean wave. In living individuals, the test is covered by a skin of velvet-textured spines which are covered with very small hairs (cilia). Coordinated movements of the spines enable sand dollars to move across the seabed. The velvety ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name is a combination of the Ancient Greek ''palaiós'' meaning "old" and the Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene". The epoch is bracketed by two major events in Earth's history. The K–Pg extinction event, brought on by Chicxulub impact, an asteroid impact and possibly volcanism, marked the beginning of the Paleocene and killed off 75% of living species, most famously the non-avian dinosaurs. The end of the epoch was marked by the Paleocene–Eocene Thermal Maximum (PETM), which was a major climatic event wherein about 2,500–4,500 gigatons of carbon were released into the atmosphere and ocean systems, causing a spike in global temperatures and ocean acidification. In the Pal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinoid
Sea urchins () are spine (zoology), spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (Test (biology), tests) of sea urchins are round and spiny, ranging in diameter from . Sea urchins move slowly, crawling with tube feet, and also propel themselves with their spines. Although algae are the primary diet, sea urchins also eat slow-moving (Sessility (motility), sessile) animals. Predation, Predators that eat sea urchins include a wide variety of fish, starfish, crabs, marine mammals. Sea urchins are also used as food especially in Japan. Adult sea urchins have fivefold symmetry, but their pluteus larvae feature Bilateral symmetry, bilateral (mirror) symmetry, indicating that the sea urchin belongs to the Bilateria group of animal phylum, phyla, which also comprises the chordates and the arthropods, the annelids and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mellita Quinquiesperforata
''Mellita quinquiesperforata'' (Leske, 1778) is a tropical species of sand dollar, a flat, round marine animal related to sea urchins, starfish, and other echinoderms. They can be found along the eastern coast of the United States and the coast of Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area .... References Clypeasteroida Animals described in 1778 {{echinoidea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinarachniidae
Echinarachniidae is a family of echinoderms belonging to the order Clypeasteroida Sand dollars (also known as a sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) are species of flat, burrowing sea urchins belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are k .... Genera Genera: * '' Astrodapsis'' Conrad, 1856 * '' Echinarachnius'' Gray, 1825 * '' Faassia'' Shmidt, 1971 References Clypeasteroida Echinoderm families {{echinoidea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinarachnius Parma
''Echinarachnius parma'', the common sand dollar, is a species of sand dollar native to the Northern Hemisphere. Kroh, A.; Mooi, R. (2020). World Echinoidea Database. Echinarachnius parma (Lamarck, 1816). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=158062 on 2020-12-31 ;Subspecies: * ''Echinarachnius parma obesus'' H.L. Clark, 1914 * ''Echinarachnius parma parma'' (Lamarck, 1816) * ''Echinarachnius parma sakkalinensis'' Argamakowa, 1934 Distribution It is found in the North Pacific and Northwest Atlantic, on the North American east coast from New Jersey north, as well as in Alaska, Siberia, British Columbia, and Japan. It inhabits isolated areas on sandy bottoms below the low tide level down to a depth of . Description The tests (shells) of these sand dollars are round, flat and disc-like, typically measuring in diameter. The entire shell is also covered with maroon-colored moveable spines. The color is a purpli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monterey Bay Aquarium
Monterey Bay Aquarium is a nonprofit public aquarium in Monterey, California. Known for its regional focus on the marine habitats of Monterey Bay, it was the first to exhibit a living kelp forest when it opened in October 1984. Its biologists have pioneered the animal husbandry of jellyfish and it was the first to successfully care for and display a great white shark. The organization's research and conservation efforts also focus on sea otters, various birds, and tunas. Seafood Watch, a sustainable seafood advisory list published by the aquarium beginning in 1999, has influenced the discussion surrounding sustainable seafood. Early proposals to build a public aquarium in Monterey County were not successful until a group of four marine biologists affiliated with Stanford University revisited the concept in the late 1970s. Monterey Bay Aquarium was built at the site of a defunct sardine cannery and has been recognized for its architectural achievements by the American Institut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eccentric Sand Dollar
''Dendraster excentricus'', also known as the eccentric sand dollar, sea-cake, biscuit-urchin, western sand dollar, or Pacific sand dollar, is a species of sand dollar in the family Dendrasteridae. It is a flattened, burrowing sea urchin found in the north-eastern Pacific Ocean from Alaska to Baja California. General information ''Dendraster excentricus'' is an irregular echinoid that is flattened and burrows into the sand, unlike the regular echinoids, or sea urchins. It can be found living in the Pacific Ocean from Alaska to Baja California. The range for ''Dendraster excentricus'' is larger and includes the range of the other two extant species of Dendraster: '' D. vizcainoensis'' and '' D. terminalis''. The flower pattern in this species is off-center, giving it the species name ''excentricus''. Its test (skeleton) is compared to that of a sea urchin below. Description They are colored gray, brown, black or shades of purple. Their size is variable, averaging 76 mm with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinocyamus Pusillus
''Echinocyamus pusillus'', commonly known as the pea urchin or green urchin, is a species of sand dollar, a sea urchin in the family Fibulariidae, native to the northeastern Atlantic Ocean and the Mediterranean Sea. It buries itself in gravel or coarse sand at depths down to about . Description ''Echinocyamus pusillus'' is a small sea urchin with a flattened, oval body up to long. The anterior end is slightly pointed. The aboral (upper) surface is convex while the oral (lower) surface is flat. The ambulacral plates widen and form a petal-like pattern on the aboral surface, and it is through each of these areas that six to nine pairs of tube feet protrude. The whole test is clad in short dense spines, giving the living animal a furry appearance; spines of two types are present, relatively long, sharply-pointed ones and shorter ones with serrated tips. The mouth is in the centre of the oral surface and the anus is also on the oral surface but further back. The colour of this sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benthos
Benthos (), also known as benthon, is the community of organisms that live on, in, or near the bottom of a sea, river, lake, or stream, also known as the benthic zone.Benthos from the Census of Antarctic Marine Life website This community lives in or near marine or freshwater sedimentary environments, from s along the , out to the , and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation tends to exist within any given population as a result of genetic mutation and recombination. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or more rare within a population. The evolutionary pressures that determine whether a characteristic is common or rare within a population constantly change, resulting in a change in heritable characteristics arising over successive generations. It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules. The theory of evolution by n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with selective breeding, artificial selection, which in his view is intentional, whereas natural selection is not. Genetic diversity, Variation exists within all populations of organisms. This occurs partly because random mutations arise in the genome of an individual organism, and their offspring can inherit such mutations. Throughout the lives of the individuals, their genomes interact with their environments to cause variations in traits. The environment of a genome includes the molecular biology in the Cell (biology), cell, other cells, other individuals, populations, species, as well as the abiotic environment. Because individuals with certain variants of the trait tend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bilateral Symmetry
Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a plane of symmetry down its centre, or a pine cone with a clear symmetrical spiral pattern. Internal features can also show symmetry, for example the tubes in the human body (responsible for transporting gases, nutrients, and waste products) which are cylindrical and have several planes of symmetry. Biological symmetry can be thought of as a balanced distribution of duplicate body parts or shapes within the body of an organism. Importantly, unlike in mathematics, symmetry in biology is always approximate. For example, plant leaves – while considered symmetrical – rarely match up exactly when folded in half. Symmetry is one class of patterns in nature whereby there is near-repetition of the pattern element, either by reflection or rotation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
