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Earthworm
An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. They occur worldwide where soil, water, and temperature allow. Earthworms are commonly found in soil, eating a wide variety of organic matter. This organic matter includes plant matter, living protozoa, rotifers, nematodes, bacteria, fungi, and other microorganisms. An earthworm's digestive system runs the length of its body. An earthworm respires (breathes) through its skin. It has a double transport system made of coelomic fluid that moves within the fluid-filled coelom and a simple, closed circulatory system. It has a central and peripheral nervous system. Its central nervous system consists of two ganglia above the mouth, one on either side, connected to a nerve running along its length to motor neurons and sensory cells in each s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lumbricina
An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. They occur worldwide where soil, water, and temperature allow. Earthworms are commonly found in soil, eating a wide variety of organic matter. This organic matter includes plant matter, living protozoa, rotifers, nematodes, bacteria, fungi, and other microorganisms. An earthworm's digestive system runs the length of its body. An earthworm respires (breathes) through its skin. It has a double transport system made of coelomic fluid that moves within the fluid-filled coelom and a simple, closed circulatory system. It has a central and peripheral nervous system. Its central nervous system consists of two ganglia above the mouth, one on either side, connected to a nerve running along its length to motor neurons and sensory cells in each s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligochaeta
Oligochaeta () is a subclass of animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms. Specifically, oligochaetes comprise the terrestrial megadrile earthworms (some of which are semiaquatic or fully aquatic), and freshwater or semiterrestrial microdrile forms, including the tubificids, pot worms and ice worms ( Enchytraeidae), blackworms ( Lumbriculidae) and several interstitial marine worms. With around 10,000 known species, the Oligochaeta make up about half of the phylum Annelida. These worms usually have few setae (chaetae) or "bristles" on their outer body surfaces, and lack parapodia, unlike polychaeta. Diversity Oligochaetes are well-segmented worms and most have a spacious body cavity (coelom) used as a hydroskeleton. They range in length from less than up to in the 'giant' species such as the giant Gippsland earthworm (''Megascolides australis'') and the Mekong worm (''Amynth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clitellum
The clitellum is a thickened glandular and non-segmented section of the body wall near the head in earthworms and leeches, that secretes a viscid sac in which eggs are stored. It is located near the anterior end of the body, between the fourteenth and seventeenth segments. The number of the segments to where the clitellum begins and the number of segments that make up the clitellum are important for identifying earthworms. In microdrile earthworms, the clitellum has only one layer, resulting in a smaller quantity of eggs than that of the megadrile earthworms, which have larger multi-layered clitellum that have special cells that secrete albumin into the worms' egg sac. The clitellum is part of the reproductive system of clitellates, a subgroup of annelids which contains oligochaetes (earthworms) and hirudineans (leeches). The clitellum is a thick, saddle-like ring found in the epidermis (skin) of the worm, usually with a light-colored pigment. To form a cocoon for its eggs, the cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former term specifically to displaced soil. Soil consists of a solid phase of minerals and organic matter (the soil matrix), as well as a porous phase that holds gases (the soil atmosphere) and water (the soil solution). Accordingly, soil is a three-state system of solids, liquids, and gases. Soil is a product of several factors: the influence of climate, relief (elevation, orientation, and slope of terrain), organisms, and the soil's parent materials (original minerals) interacting over time. It continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion. Given its complexity and strong internal connectedness, soil ecologists regard soil as an ecosystem. Most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skeleton
A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside the body, and the hydroskeleton, a flexible internal skeleton supported by fluid pressure. Vertebrates are animals with a vertebral column, and their skeletons are typically composed of bone and cartilage. Invertebrates are animals that lack a vertebral column. The skeletons of invertebrates vary, including hard exoskeleton shells, plated endoskeletons, or Sponge spicule, spicules. Cartilage is a rigid connective tissue that is found in the skeletal systems of vertebrates and invertebrates. Etymology The term ''skeleton'' comes . ''Sceleton'' is an archaic form of the word. Classification Skeletons can be defined by several attributes. Solid skeletons consist of hard substances, such as bone, cartilage, or cuticle. These can be further ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrostatic Skeleton
A hydrostatic skeleton, or hydroskeleton, is a flexible skeleton supported by fluid pressure. Hydrostatic skeletons are common among simple invertebrate organisms. While more advanced organisms can be considered hydrostatic, they are sometimes referred to as hydrostatic for their possession of a hydrostatic organ instead of a hydrostatic skeleton. A hydrostatic organ and a hydrostatic skeleton may have the same capabilities, but they are not the same. Hydrostatic organs are more common in advanced organisms, while hydrostatic skeletons are more common in primitive organisms. As its name suggests, containing hydro meaning "water", being hydrostatic means that the skeleton or organ is fluid-filled. As a skeletal structure, it possesses the ability to affect shape and movement, and involves two mechanical units: the muscle layers and the body wall. The muscular layers are longitudinal and circular, and part of the fluid-filled coelom within. Contractions of the circular muscles lengt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermaphrodite
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrates) do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the female or male. For example, the great majority of tunicata, tunicates, pulmonate molluscs, opisthobranch, earthworms, and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also hermaphrodites. Animal species having different sexes, male and female, are called Gonochorism, gonochoric, which is the opposite of hermaphrodite. There are also species where hermaphrodites exist alongside males (called androdioecy) or alongside females (called gynodioecy), or all three exist in the same species ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Setae
In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. They help, for example, earthworms to attach to the surface and prevent backsliding during peristaltic motion. These hairs make it difficult to pull a worm straight from the ground. Setae in oligochaetes (a group including earthworms) are largely composed of chitin. They are classified according to the limb to which they are attached; for instance, notosetae are attached to notopodia; neurosetae to neuropodia. Crustaceans have mechano- and chemosensory setae. Setae are especially present on the mouthparts of crustaceans and can also be found on grooming limbs. In some cases, setae are modified into scale like structures. Setae on the legs of krill and other small crustaceans help them to gather phytoplankton. It captures them and allows ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megadrile
A megadrile is a kind of worm, a mostly terrestrial oligochaete. Megadriles are placed within the superorder Megadrilacea, and include Moniligastrida and Lumbricina (or the order Haplotaxida The Haplotaxida are one of two orders within the annelid subclass Oligochaeta, the other being the Lumbriculida. No real common name exists, but they are simply referred to as haplotaxids. Given that the other clitellatan annelids are embedd ..., following Easton). References Clitellata Invertebrate common names {{Annelid-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opisthopora
Opisthopora is an order of mostly terrestrial worms. It is an order of the subclass Oligochaeta, which is distinguished by meganephridiostomal, male pores which open posteriorly to the last testicular segment. It includes the megadrile families of the mostly terrestrial true earthworms. There are currently eight known families. Families * Eudrilidae * Glossoscolecidae * Lumbricidae * Megascolecidae * Moniligastridae * Ocnerodrilidae * Octochaetidae Octochaetidae is a family of annelids The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exi ... References Clitellata {{Annelid-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Body Plan
A body plan, ( ), or ground plan is a set of morphological features common to many members of a phylum of animals. The vertebrates share one body plan, while invertebrates have many. This term, usually applied to animals, envisages a "blueprint" encompassing aspects such as symmetry, layers, segmentation, nerve, limb, and gut disposition. Evolutionary developmental biology seeks to explain the origins of diverse body plans. Body plans have historically been considered to have evolved in a flash in the Ediacaran biota; filling the Cambrian explosion with the results, and a more nuanced understanding of animal evolution suggests gradual development of body plans throughout the early Palaeozoic. Recent studies in animals and plants started to investigate whether evolutionary constraints on body plan structures can explain the presence of developmental constraints during embryogenesis such as the phenomenon referred to as phylotypic stage. History Among the pioneering zoologist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplotaxida
The Haplotaxida are one of two orders within the annelid subclass Oligochaeta, the other being the Lumbriculida. No real common name exists, but they are simply referred to as haplotaxids. Given that the other clitellatan annelids are embedded between and around the Haplotaxida and Lumbriculida, the traditional ''Oligochaeta'' are a paraphyletic assemblage. Thus, the Haplotaxida might eventually be up-ranked to subclass status within the ''Clitellata'' or an expanded Oligochaeta, with the present suborders advancing to order rank. The latter – though without merging the ''Oligochaeta'' and ''Clitellata'' – has been proposed time and again in the past, most prominently for the distinct '' Moniligastrina.'' Families Of the four suborders of Haplotaxida, two are minor lineages, monotypic at family level. Another one, the Tubificina, is sizeable and contains the aquatic worms, while the fourth, the earthworms or Lumbricina, unites the bulk of the order's families: Suborder H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
