Hemichordata: They are tongue worms, which have been included for long as a subphylum or class of Phylum Chordata in the lower chordates or Protochordata, but now they are placed as an independent phylum of invertebrates, since their supposed affinities with chordates are doubtful. Hemichordata are a small group of marine, solitary or colonial, worm-like,…
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Phylum Protozoa: The Phylum Protozoa comprising a diverse group of unicellular organisms. Let’s explore their characteristics and classification. Defination: The Protozoa may be defined as ‘microscopic, acellular animalcules existing singly or colonies, without tissues and organs, having one or more nuclei. When in colonies, they differ from Metazoa in having all the individuals alike except…
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Phylum Cnidaria: Cnidaria derives from the Greek word “cnidos,” which means “stinging thread.” Defination: The cnidaria may be defined as “diploblastic Metazoa with tissue grade of construction having nematocysts and a single gastrovascular cavity or the coelenteron.” The phylum Cnidaria is a large group of aquatic invertebrates, with over 11,000 described species. They are mostly marine…
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Phylum Arthropoda: Arthropods are the largest phylum in the animal kingdom, making up over two-thirds of all known animal species. They are incredibly diverse and can be found in almost every habitat on Earth, from the deepest oceans to the highest mountains. Here are some of the general characteristics of arthropods General Characters of Phylum…
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Phylum Mollusca: It is the second largest phylum in animal kingdom and consists of over 150,000 marine, freshwater and terrestrial species. Mollusca, the second largest animal phylum after Arthropoda, is a diverse group of soft-bodied invertebrates . They are found in almost all aquatic environments, from freshwater to the deepest parts of the ocean, as…
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Annelida: The phylum annelida was first coined by LAMARCK (1801) (Gr., annulus – little ring + eidos – form) for the higher segmented worms. There are around 16500 species included in the phylum Annelida. Appearence of metamerism represents their greatest Advancement, so they are called a Segmented worms. The unique characteristic of the phylum Annelida is metamerism….
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Aschelminthes: It also referred to as Nemathelminthes, it is an invertebrates phylum which includes roundworms. Defination: They are bilaterally symmetrical, triploblastic and pseudocoelomate animals with organ system of organization. Excretion involves a giant excretory cell called Renette cell. They have tube-within-tube type of body plan. Nemathelminthes group are created by Gwgenbaur in 1859 to place…
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