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Holothuria Mexicana
''Holothuria mexicana'', the donkey dung sea cucumber, is commonly found in the Caribbean Sea, Caribbean and the Azores. It is a commercially important aspidochirote (sediment feeding) sea cucumber that can reach a total length of . Description This sea cucumber is transversely wrinkled and reaches in total length. It has a top surface that is dull brown or grey with occasional warts. The bottom surface is reddish, orange or pale and is uniformly covered in tube feet.Collin, R., M.C. Díaz, J. Norenburg, R.M. Rocha, J.A. Sánchez, A. Schulze. M. Schwartz and A. Valdés. 2005. Photographic identification guide to some common marine invertebrates of Bocas Del Toro, Panama. Caribbean Journal of Science. 41(3): 638-707. Populations are unimodal and have a 1:1 male to female sex ratio.Guzman, H.M., C.A. Guevara, I.C. Hernandez. 2003. Reproductive cycle of two commercial species of sea cucumber (Echinodermata: Holothuroidea) from Caribbean Panama. Marine Biology 142: 271–279. Distri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ludwig Diels
Dr. Friedrich Ludwig Emil Diels (24 September 1874 – 30 November 1945) was a German botanist. Diels was born in Hamburg, the son of the classical scholar Hermann Alexander Diels. From 1900 to 1902 he traveled together with Ernst Georg Pritzel through South Africa, Java, Australia and New Zealand. Shortly before the First World War he travelled New Guinea and in the 1930s in Ecuador. Especially his collections of plants from Australia and Ecuador, which contained numerous holotypes, enriched the knowledge of the concerning floras. His monography on the Droseraceae from 1906 is still a standard. The majority of his collections were stored at the botanical garden in Berlin-Dahlem, whose vicedirector he had been since 1913, becoming its director in 1921 until 1945. His collections were destroyed there during an air raid in 1943. He died in Berlin on 30 November 1945. Honours Several genus of plants have been named after him including; ''Dielsantha'' (from ''Campanulaceae' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protozoa
Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Historically, protozoans were regarded as "one-celled animals", because they often possess animal-like behaviours, such as motility and predation, and lack a cell wall, as found in plants and many algae. When first introduced by Georg Goldfuss (originally spelled Goldfuß) in 1818, the taxon Protozoa was erected as a class within the Animalia, with the word 'protozoa' meaning "first animals". In later classification schemes it was elevated to a variety of higher ranks, including phylum, subkingdom and kingdom, and sometimes included within Protoctista or Protista. The approach of classifying Protozoa within the context of Animalia was widespread in the 19th and early 20th century, but not universal. By the 1970s, it became usual to require th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and borders fourteen countries by land, the most of any country in the world, tied with Russia. Covering an area of approximately , it is the world's third largest country by total land area. The country consists of 22 provinces, five autonomous regions, four municipalities, and two Special Administrative Regions (Hong Kong and Macau). The national capital is Beijing, and the most populous city and financial center is Shanghai. Modern Chinese trace their origins to a cradle of civilization in the fertile basin of the Yellow River in the North China Plain. The semi-legendary Xia dynasty in the 21st century BCE and the well-attested Shang and Zhou dynasties developed a bureaucratic political system to serve hereditary monarchies, or dyna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface-supplied Diving
Surface-supplied diving is diving using equipment supplied with breathing gas using a diver's umbilical from the surface, either from the shore or from a diving support vessel, sometimes indirectly via a diving bell. This is different from scuba diving, where the diver's breathing equipment is completely self-contained and there is no link to the surface. The primary advantages of conventional surface supplied diving are lower risk of drowning and considerably larger breathing gas supply than scuba, allowing longer working periods and safer decompression. Disadvantages are the absolute limitation on diver mobility imposed by the length of the umbilical, encumbrance by the umbilical, and high logistical and equipment costs compared with scuba. The disadvantages restrict use of this mode of diving to applications where the diver operates within a small area, which is common in commercial diving work. The copper helmeted free-flow standard diving dress is the version which made com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snorkelling
Snorkeling ( British and Commonwealth English spelling: snorkelling) is the practice of swimming on or through a body of water while equipped with a diving mask, a shaped breathing tube called a snorkel, and usually swimfins. In cooler waters, a wetsuit may also be worn. Use of this equipment allows the snorkeler to observe underwater attractions for extended periods with relatively little effort and to breathe while face-down at the surface. Snorkeling is a popular recreational activity, particularly at tropical resort locations. It provides the opportunity to observe underwater life in a natural setting without the complicated equipment and training required for scuba diving. It appeals to all ages because of how little effort is involved and is the basis of the two surface disciplines of the underwater sport of finswimming. Snorkeling is also used by scuba divers when on the surface, in underwater sports such as underwater hockey and underwater rugby, and as part of water-ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fertilization
Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Processes such as insemination or pollination which happen before the fusion of gametes are also sometimes informally called fertilisation. The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation. History In Antiquity, Aristotle conceived the formation of new individuals through fusion of male and female fluids, with form and function emerging gradually, in a mode called by him as epigenetic. In 1784, Spallanzani established the need of interaction between the female's ovum and male's sperm to form a zygote in frog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gametes
A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual that produces the larger type of gamete—called an ovum— and a male produces the smaller type—called a sperm. Sperm cells or spermatozoa are small and motile due to the flagellum, a tail-shaped structure that allows the cell to propel and move. In contrast, each egg cell or ovum is relatively large and non-motile. In short a gamete is an egg cell (female gamete) or a sperm (male gamete). In animals, ova mature in the ovaries of females and sperm develop in the testes of males. During fertilization, a spermatozoon and ovum unite to form a new diploid organism. Gametes carry half the genetic information of an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonopore
A gonopore, sometimes called a gonadopore, is a genital pore in many invertebrates. Hexapods, including insects have a single common gonopore, except mayflies, which have a pair of gonopores. More specifically, in the unmodified female it is the opening of the common oviduct, and in the male, it is the opening of the ejaculatory duct. The position of the gonopore varies considerably between groups, but is generally constant within groups, allowing its position to be used as a "segmental marker". In Malacostraca, it is on the sixth thoracic segment; in Symphyla it is on the fourth trunk segment; in arachnids, it is on the second segment of the opisthosoma. In insects and centipedes, the gonopores are close to the animal's tail, while in millipedes they are on the third body segment behind the head, near the second pair of legs. See also * Gonopod * Gonopodium Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curaçao
Curaçao ( ; ; pap, Kòrsou, ), officially the Country of Curaçao ( nl, Land Curaçao; pap, Pais Kòrsou), is a Lesser Antilles island country in the southern Caribbean Sea and the Dutch Caribbean region, about north of the Venezuela coast. It is a constituent country of the Kingdom of the Netherlands. Together with Aruba and Bonaire, it forms the ABC islands. Collectively, Curaçao, Aruba, and other Dutch islands in the Caribbean are often called the Dutch Caribbean. Curaçao was formerly part of the Curaçao and Dependencies colony from 1815 to 1954 and later the Netherlands Antilles from 1954 to 2010, as Island Territory of Curaçao ( nl, Eilandgebied Curaçao, links=no, pap, Teritorio Insular di Kòrsou, links=no), and is now formally called the Country of Curaçao. It includes the main island of Curaçao and the much smaller, uninhabited island of Klein Curaçao ("Little Curaçao"). Curaçao has a population of 158,665 (January 2019 est.), with an area of ; its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Florida
Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to the south by the Straits of Florida and Cuba; it is the only state that borders both the Gulf of Mexico and the Atlantic Ocean. Spanning , Florida ranks 22nd in area among the 50 states, and with a population of over 21 million, it is the third-most populous. The state capital is Tallahassee, and the most populous city is Jacksonville. The Miami metropolitan area, with a population of almost 6.2 million, is the most populous urban area in Florida and the ninth-most populous in the United States; other urban conurbations with over one million people are Tampa Bay, Orlando, and Jacksonville. Various Native American groups have inhabited Florida for at least 14,000 years. In 1513, Spanish explorer Juan Ponce de León became the first k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. Mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period. Description Crabs are generally covered with a thick exoskeleton, composed primarily of highly mineralized chitin, and armed with a pair of chelae (claws). Crabs vary in size from the pea crab, a few millimeters wide, to the Japanese spider crab, with a leg span up to . Several other groups of crustaceans with similar appearances – such as king crabs and porcelain crabs – are not true crabs, but have evolved features similar to true crabs through a process known as carcinisation. Environment Crabs are found in all of the world's oceans, as well as in fresh w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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