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Which are deuterosomes?
Deuterostomes are a major group of bilaterian organisms that include vertebrates, echinoderms, and some other invertebrates. They are characterized by a developmental pattern in which the first opening formed during gastrulation becomes the anus, with the mouth developing secondarily. This is in contrast to protostomes, where the first opening becomes the mouth.
Do arthropods develop from three embryonic germ layers?
Yes, arthropods develop from three embryonic germ layers: ectoderm, mesoderm, and endoderm. The ectoderm forms the outer body covering and nervous system, the mesoderm gives rise to muscles and the circulatory system, and the endoderm develops into the digestive tract. This triploblastic organization is a characteristic feature of bilaterian animals, which includes arthropods.
What are the five different animal kingdoms?
The 5 main invertebrates are:Porifera (Ex: sponges)Cnidaria (Ex: jellyfish)Other Bilaterian: Nematoda, Arthropoda, Mollusca, and AnnelidaEchinodermata (Ex: sea urchins)Chordata (Ex: hagfish)
What are the differences between the central nervous system and the autonomic nervous system?
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals and the endocrine system is a system of glands, each of which secretes a type of hormone directly into the bloodstream to regulate the body.
What is the Difference between protonephridia and metanephridia?
Two different kinds of nephridia occur within the Bilateria, protonephridia closed up by a termi- nal cell and metanephridia opening into the coelomic cavity. Both initially filter and subsequently modify intercellular fluids. Whereas metanephridia are strictly correlated to a coelom, proto- nephria occur in acoelomate as well as in coelomate organisms. Protonephridia of different bilaterian taxa correspond to each other in several structural fea- tures. Therefore, it is hypothesized that protonephridia are homologous organs throughout the Bilateria. They must have evolved once as one pair of monociliated organs originating from the ectoderm and consisting of one terminal, one duct and one nephropore cel!. In the ground pattern of the Bilateria the cilium of the terminal cell has only one rootlet and is surrounded by presumably eight strengthened and elongated microvilli. Cilium and microvilli extend into the hollow cylinder of the terminal cell, which is oriented distally and is attached to the adjacent duct cell by desmosomes. This cylinder is perforated by clefts and represents the supporting structure of the filtration barrier consisting of extracellular matrix. In the Annelida and Phoronida, the metanephridia at the postlarval stages are ontogenetically preceded by protonephridia in the larva, but far reaching structural and developmental differ- ences exist between the metanephridia of both. In phoronids the/rotonephridial duct of the larva is retained in the postlarva and acquires a coelothelially derive funnel, whereas in annelids the metanephridia are uniform organs originating from a solid anlage, which is a repetition of the protonephridial anlage of the larva. The differences contradict a homology of the metanephridia In Annelida and Phoronida. We therefore have to conclude that metanephridia must have evolved independently, at least two times. The comparative analysis of nephridia in the Bilateria allows the following hypothesis: Pro- tonephridia were evolved in a monophasic acoelomate organism in the stem lineage of the Bilateria. During the evolution of biphasic life cycles consisting of an acoelomate larva and a coelomate adult, the information about the differentiation of protonephridia has been preserved in the early acoelomate developmental (larval) stages. During postlarval development and the formation of a coelom the protonephridia have either been retained or moditied into meta- nephridia. According to the differences between the metanephridia of phoronids and annelids, we emphasize that there is no possibility to trace back all bilaterian taxa with a coelom to a common stem species.fromsania zulfiqar kaimkhani
What animals are in the flatworm group?
The flatworms, or Platyhelminthes or Plathelminthes are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates, (having no body cavity), and no specialized circulatory and respiratory organs, which restricts them 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 the ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food cannot be processed continuously. In traditional zoology texts, Platyhelminthes are divided into Turbellaria, which are mostly nonparasitic 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 is now deprecated. Free-living flatworms are mostly predators, and live in water or in shaded, humid terrestrial environments such as leaf litter. Cestodes (tapeworms) and trematodes (flukes) have complex life-cycles, with mature stages that live as parasites in the digestive systems of fish or land vertebrates, and intermediate stages that infest secondary hosts. The eggs of trematodes are excreted from their main hosts, whereas adult cestodes generate vast numbers of hermaphroditic, segment-like proglottids which detach when mature, are excreted, and then release eggs. Unlike the other parasitic groups, the monogeneans are external parasites infesting aquatic animals, and their larvae metamorphose into the adult form after attaching to a suitable host. United Nations Farms
What are living things organized into?
At their simplest, broadest level, living organisms are classified into domains according to whether their cells are nucleated or non-nucleated and according to the structure of their cells' membranes. The domains are Eukarya (nucleated organisms) and two prokaryotic domains differentiated by cell membrane detail (among other things): Archaea and Bacteria.Domains are further divided into kingdoms. Eukarya, for example, is divided into the plant kingdom, animal kingdom, fungal kingdom and protist kingdom. The protists should actually be classified as many kingdoms due to their diversity. Plants, animals and fungi are differentiated on cell wall structure and cell structure. Plants have cellulose cell walls, fungi have chitinous cell walls and animals lack cell walls. Plants contain chloroplasts, which animals and fungi lack. Animals contain centrioles which plants and fungi mostly lack. Animals and plants are all multicellular whereas some fungi are unicellular (such as Saccharomyces).Kingdoms are divided into phyla. There are 12 phyla of plants and just over 30 phyla of animals and a few fungal phyla. The singular of phyla is phylum by the way. Through their phyla, plants show increasing sporophyte dominance and decreasing gametophyte dominance. Primitive plants such as bryophytes are gametophyte dominant whereas all other plants are sporophyte dominant, but increasingly so thoughout the evolution of plants, from really dominant bryophyte gametophytes to the really diminutive and shrunken gametophytes of angiosperms. Some of the phyla of plants are: Hepatophyta, Bryophyta/Musci, Anthocerotophyta, Pteridophyta, Equisetophyta, Ginkgophyta, Pinophyta, Cycadophyta, Gnetophyta, Anthophyta.Note that "kingdom" and "phylum" are major subdivisions (taxa): there are intermediates. In the animal kingdom, there is a distinction between Radiata and Bilateria which are "unranked" taxa, not kingdoms and not phyla but between the two (and not subkingdoms or superphyla either in case you wonder). Radiata contains radially symmetrical animals such as the phyla Cnidaria and Ctenophora (jellyfish + corals and comb jellies respectively). Bilateria contains the bilaterally symmetrical animals which may be further classified as coelomate, acoelomate or pseudocoelomate according to the advancedness of their body cavities. Some bilaterian phyla include Platyhelminthes, Mollusca, Annelida, Arthropoda, Nemertea, Nematoda, Chaetognatha, Sipuncula, Echinodermata, Chordata, Hemichordata and Xenoturbellida.You see the pattern by now. Division after division in the taxonomic hierarchy: Kingdom, Phylum, Class, Order, Family, Genus, Species. Linnaeus (the "father" of classification) no doubt grouped organisms solely on morphology. Now, we use molecular data and that can refute or confirm morphological hypotheses of classification. Linnaeus grouped on "likeness"/similarity, no doubt oblivious to evolutionary relationship or genetic relationship (Darwin published Origin about a century after Linnaeus did anything useful) and, in those days, species were declared immutable creations. No-one knew of Mendel, no-one knew of Darwin, no-one knew of the concept of monophyly. But, these days, classification must reflect evolutionary relations where groups are monophyletic (a monophyly comprises a common ancestor and all its descendents). Mammals are a monophyly. All platypuses, marsupials and placental mammals all share a common ancestor. Reptiles are techincally not a monophyly. The common ancestor of all reptiles is also the common ancestor of all birds. If one excludes "bird" when one talks of reptiles, trying to say that birds are not reptiles, then "Reptilia" is not a monophyly.Classification is of course a war and a half. There are those who are disposed to "lumping" and those inclined to "splitting". For example, someone who says a Giant Panda is a "Bear" "lumps" this species in the Family Ursidae. Someone who declares a Giant Panda is too distinct to be an ursid "splits" the Giant Panda into a separate family, Ailuridae. Cats, including lynxes, used to almost all be in the genus Felis. Now, they have been split into many genera. In fact, caracals and lynxes (both lynxes by the common tongue) are split into two separate genera themselves. The same story about cats is similar to the story about albatrosses and sunbirds. Goodness, the battle does go on.
