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Gastrovascular Cavity
The gastrovascular cavity is the primary organ of digestion and circulation in two major animal phyla: the Coelenterates or cnidarians (including jellyfish and corals) and Platyhelminthes (flatworms). The cavity may be extensively branched into a system of canals. In cnidarians, the gastrovascular system is also known as the coelenteron, and is commonly known as a "blind gut" or "blind sac", since food enters and waste exits through the same orifice. The radially symmetrical cnidarians have a sac-like body in two distinct layers, the epidermis and gastrodermis, with a jellylike layer called the mesoglea between. Extracellular digestion takes place within the central cavity of the sac-like body. This cavity has only one opening to the outside which, in most cnidarians, is surrounded by tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flower Hat Jelly
The flower hat jelly (''Olindias formosus'') is a species of hydrozoa, hydromedusa in the hydrozoan family Olindiidae. Although they look like a jellyfish, they actually belong in the class Hydrozoa, while true jellyfish belong in class Scyphozoa. Flower hat jellies occur in the northwestern Pacific off central and southern Japan, and South Korea's Jeju Island.Patry, W.; T. Knowles; L. Christianson; M. Howard (2014). The hydroid and early medusa stage of Olindias formosus (Cnidaria, Hydrozoa, Limnomedusae). Journal of the Marine Biological Association of the United Kingdom 94(7): 1409–1415. (close relatives live elsewhere, like ''Olindias sambaquiensis, O. sambaquiensis'' found off Argentina and Brazil). The adult form of the flower hat jelly only lives a few months and is typically seen from December to July, with peaks in April and May. During the day they rest on the bottom, often among rocks or algae, but at night they float up to hunt for their prey, typically small fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dugesia
''Dugesia'' is a genus of freshwater planarians in the family Dugesiidae triclads and the type genus of this family. These common flatworms are found in freshwater habitats of Africa, Eurasia, and Australia. ''Dugesia'' is best known to non-specialists because of its regeneration capacities. Description ''Dugesia'' species have an elongated body with a slightly triangle-shaped head. They often have grey, brown, or black dorsal color, whereas the ventral surface is usually paler. These animals have a couple of eyes constituted by a multicellular pigmented cup with many retinal cells to detect the amount of light in the nearby environment. Sometimes they present supernumerary eyes. At the anterior part of the body, behind the eye level, they have a pair of structures called auricles that give the triangle look to the 'head' and allow them to detect the intensity of water current. These auricles are free of pigment and rhabdites. Each side of the anterior margin of the head has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digestion
Digestion is the breakdown of large insoluble food compounds into small water-soluble components so that they can be absorbed into the blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream. Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion. The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes. Mechanical digestion takes place in the mouth through Chewing, mastication and in the small intestine through segmentation contractions. In chemical digestion, enzymes break down food into the small compounds that the body can use. In the human digestive system, food enters the mouth and mechanical digestion of the food starts by the action of mastication (chewing), a form of mechanical digestion, and the wetting contact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circulatory System
In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of the heart and blood vessels (from Greek meaning ''heart'', and Latin meaning ''vessels''). The circulatory system has two divisions, a systemic circulation or circuit, and a pulmonary circulation or circuit. Some sources use the terms ''cardiovascular system'' and ''vascular system'' interchangeably with ''circulatory system''. The network of blood vessels are the great vessels of the heart including large elastic arteries, and large veins; other arteries, smaller arterioles, capillaries that join with venules (small veins), and other veins. The circulatory system is closed in vertebrates, which means that the blood never leaves the network of blood vessels. Many invertebrates such as arthropods have an open circulatory system with a he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cnidaria
Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, sea anemones, corals and some of the smallest marine parasites. Their distinguishing features are an uncentralized nervous system distributed throughout a gelatinous body and the presence of cnidocytes or cnidoblasts, specialized cells with ejectable flagella used mainly for envenomation and capturing prey. Their bodies consist of mesoglea, a non-living, jelly-like substance, sandwiched between two layers of epithelium that are mostly one cell (biology), cell thick. Cnidarians are also some of the few animals that can reproduce both sexually and asexually. Cnidarians mostly have two basic body forms: swimming medusa (biology), medusae and sessility (motility), sessile polyp (zoology), polyps, both of which are radially symmetrical with mou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jellyfish
Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals, although a few are anchored to the seabed by stalks rather than being motile. They are made of an umbrella-shaped main body made of mesoglea, known as the ''bell'', and a collection of trailing tentacles on the underside. Via pulsating contractions, the bell can provide propulsion for animal locomotion, locomotion through open water. The tentacles are armed with cnidocyte, stinging cells and may be used to capture prey or to defend against predators. Jellyfish have a complex biological life cycle, life cycle, and the medusa is normally the sexual phase, which produces planula larvae. These then disperse widely and enter a sedentary #Life cycle, polyp phase which may include asexual budding before reaching sexual maturity. Jellyfish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corals
Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral reef, reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. A coral "group" is a colony of very many cloning, genetically identical polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in height. A set of tentacles surround a central mouth opening. Each polyp excretes an exoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously overnight, often around a full moon. Fertilized eggs form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platyhelminthes
Platyhelminthes (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates commonly called flatworms or flat worms. Being acoelomates (having no body cavity), and having no specialised circulatory and respiratory organs, they are restricted to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food can not be processed continuously. In traditional medicinal texts, Platyhelminthes are divided into Turbellaria, which are mostly non- parasitic animals such as planarians, and three entirely parasitic groups: Cestoda, Trematoda and Monogenea; however, since the turbellarians have since been proven not to be monophyletic, this classification i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radial 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, the face of a human being has a plane of symmetry down its centre, or a pine cone displays 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. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastrodermis
Gastrodermis (from Ancient Greek: , , "stomach"; , , "skin") is the inner layer of Cell (biology), cells that serves as a lining membrane of the gastrovascular cavity in cnidarians. It is distinct from the outer epidermis and the inner dermis and is primarily associated with the ventral side of cnidarians. It is composed of specialized cells responsible for several vital Physiology, physiological processes. The term is also used for the Analogy, analogous inner Epithelium, epithelial layer of ctenophores. Functions The gastrodermis has a role in many Biology, biological functions, including Respiration (physiology), respiration, pigmentation, and digestion. * The gastrodermis provides a large surface area for gas exchange to occur, via cutaneous respiration, which involves the exchange of oxygen and carbon dioxide through the skin. * The gastrodermis contains specialised cells called chromatophores, which are responsible for producing and controlling pigmentation. These cells co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesoglea
Mesoglea refers to the extracellular matrix found in cnidarians like coral or jellyfish as well as ctenophores that functions as a hydrostatic skeleton. It is related to but distinct from mesohyl, which generally refers to extracellular material found in sponges. Description The mesoglea is mostly water. Other than water, the mesoglea is composed of several substances including fibrous proteins, like collagen and heparan sulfate proteoglycans. The mesoglea is mostly acellular, but in both Cnidaria and Ctenophora the mesoglea contains muscle bundles and nerve fibres. Other nerve and muscle cells lie just under the epithelial layers. The mesoglea also contains wandering amoebocytes that play a role in phagocytosing debris and bacteria. These cells also fight infections by producing antibacterial chemicals. The mesoglea may be thinner than either of the cell layers in smaller coelenterates like a hydra or may make up the bulk of the body in larger jellyfish. The mesoglea serves as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tentacle
In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work mainly like muscular hydrostats. Most forms of tentacles are used for grasping and feeding. Many are sensory organs, variously receptive to touch, vision, or to the smell or taste of particular foods or threats. Examples of such tentacles are the eyestalks of various kinds of snails. Some kinds of tentacles have both sensory and manipulatory functions. A tentacle is similar to a cirrus, but a cirrus is an organ that usually lacks the tentacle's strength, size, flexibility, or sensitivity. A nautilus has cirri, but a squid has tentacles. Invertebrates Molluscs Many molluscs have tentacles of one form or another. The most familiar are those of the pulmonate land snails, which usually have two sets of tentacles on the head: when ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
