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Platyzoa

(Infrakingdom)

Overview

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A taxonomic infrakingdom.

Photos

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Taxonomy

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The Infrakingdom Platyzoa is a member of the Branch Protostomia. Here is the complete "parentage" of Platyzoa:

The Infrakingdom Platyzoa is further organized into finer groupings including:

Phyla

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Acanthocephala

The Acanthocephala ( a?a????, akanthos, thorn + ?efa??, kephale, head) is a phylum of parasitic worms known as acanthocephales, thorny-headed worms, or spiny-headed worms, characterised by the presence of an evertable proboscis, armed with spines, which it uses to pierce and hold the gut wall of its host. Acanthocephalans typically have complex life cycles, involving a number of hosts, including invertebrates, fishes, amphibians, birds, and mammals. About 1150 species have been described. [more]

Acoelomorpha

[more]

Cycliophora

Symbion is the name of a of aquatic animals, less than ½ mm wide, found living attached to the bodies of cold-water lobsters. They have sac-like bodies, and three distinctly different forms in different parts of their two-stage life-cycle. They appear so different from other animals that they were assigned their own, new phylum Cycliophora shortly after they were discovered in 1995. This was the first new phylum of multicelled organism to be discovered since the Loricifera in 1983. [more]

Gastrotricha

The gastrotrichs (from ?aste?, gaster "stomach" and ????, thrix "hair") are a phylum of microscopic (0.06-3.0 mm) animals abundant in fresh water and marine environments. Most fresh water species are part of the periphyton and benthos. Marine species are found mostly interstitially in between sediment particles. The Gastrotrich has the shortest life span of all animals, living for just 3 days. [more]

Gnathostomulida

Gnathostomulids, or jaw worms, are a small phylum of nearly microscopic marine . Most measure between 0.5 and 1 mm long. Like flatworms they have a ciliated epidermis, but are unique in having but one cilium per cell. They have no body cavity, and no circulatory or respiratory system. Each gnathostomulid is simultaneously hermaphrodite, possessing an ovary and a testis. They are characterized by a specialized, muscular jaw, which they use to scrape smaller organisms off of the grains of sand that make up their anoxic seabed mud habitat. This bilaterally symmetrical pharynx with its complex cuticular mouth parts make them appear closely related to rotifers and their allies, together making up the Gnathifera. [more]

Platyhelminthes

The flatworms, known in scientific literature as Platyhelminthes (from the p?at?, platy, meaning "flat" and ??µ??? (root: ??µ???-), helminth-, meaning worm) are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrate animals. Unlike other bilaterians they have no body cavity, and no specialized circulatory and respiratory organs, which restricts them to flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. [more]

Rotifera

The rotifers make up a of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John Harris in 1696, and other forms were described by Anton van Leeuwenhoek in 1703. Most rotifers are around 0.1–0.5 mm long (although their size can range from 50µm to over 2 millimeters), and are common in freshwater environments throughout the world with a few saltwater species. Some rotifers are free swimming and truly planktonic, others move by inchworming along the substrate, and some are sessile, living inside tubes or gelatinous holdfasts that are attached to a substrate. About 25 species are colonial (e.g., Sinantherina semibullata), either sessile or planktonic. Rotifers play an important part of the freshwater zooplankton, being a major foodsource and with many species also contributing to the decomposition of soil. [more]

At least 2,421 species and subspecies belong to the Phylum Rotifera.

More info about the Phylum Rotifera may be found here.

Sources

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Last Revised: September 22, 2009
2009/09/22 05:53:36