In this article we will discuss about of Phylum Loricifera: 1. Features of Phylum Loricifera 2. Phylogeny of Phylum Loricifera 3. Phylogenetic Relationship. An introduction to the biology, classification and ecology of Brush Heads the Phylum Loricifera. Figure 1: The phylum Loricifera. From: Palaeontology: Darwin's dilemma dissolved. Figure 1. Phylogeny of Loricifera showing key anatomical and ecological.
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By considering morphological and larval features it may be considered that loriciferans, priapulids, kinorhynchs and nematomorphs may have derived from phylum loricifera common ancestor.
The phylogeny of aschelminthes is a most controversial issue. Historically the aschelminthes were claimed as monophyletic for some morphological grounds, such as the pseudocoelom, phylum loricifera thick tough cuticle which is often moulted, and adhesive organs.
Phylum loricifera a single character is not universally present among the different phyla of Aschelminthes. Pseudocoelom is not present among the members of gastrotrichs, some small-sized nematodes and kinorhynchs.
So pseudocoelom is not most distinctive feature for aschelminthes. The asexual part of the life cycle phylum loricifera of two types of feeding animals.
Loriciferans - Loricifera - Overview - Encyclopedia of Life
The first type houses phylum loricifera so-called Pandora larva, the second type houses the primary male and female inside a brooding chamber. Furthermore, the sessile animal shows internal budding, whereby it loses the head buccal funnel and entire digestive system, replacing them with a new bud arising from phylum loricifera cells in the posterior part of the trunk.
This process of internal phylum loricifera is repeated several times in the life of the sessile animal and is coupled to the asexual formation of the Pandora larva.
The Pandora larva forms a new feeding-stage, also by internal budding.
Animal Phyla/Loricifera - Wikiversity
It settles very close to the maternal individual, and in this way the phylum loricifera can multiply very quickly phylum loricifera completely cover the mouth limbs of its host. Later, the feeding stages may switch to produce a primary male or a sexually mature female instead of the Pandora larva.
This marks the beginning of the sexual part of the life cycle. The primary male is released from the brooding chamber without a penis or a true testis.
phylum loricifera It settles on a feeding animal. Only if there is a young female inside this feeding animal can the attached primary male develop one or two new secondary males inside by internal asexual budding.
Each secondary male has a tubular cuticular penis phylum loricifera a single compartment with spermatozoa. The female is about double the size of the primary male, and she looks similar to the Pandora larva except for lacking internal budding; phylum loricifera anteriorly she has a single large oocyte.
Fertilisation of the egg occurs inside the female, perhaps just before or during the release of the female from the brooding chamber. She settles very close to her maternal feeding animal, and broods inside phylum loricifera a new type of larva, the chordoid larva, so named after a mesodermal chordoid structure of approximate 50 stacked muscle cells see Funch, The growing larva engulfs all her tissue, leaving only the cuticle.
The Brush Heads (Phylum Loricifera)
The chordoid larva hatches from the female exuvium, head first. It is a good swimmer and represents the dispersal stage. This phylum loricifera settles on a new host and phylum loricifera internal budding forms a new feeding animal, so a new life cycle can begin.
The complex life cycle of Symbion pandora as illustrated in Figure 2 differs from the original description only by the recognition of the free swimming secondary male Fig.
The type species was found on the Norway lobster, Nephrops norvegicus from Scandinavian waters. More recently two other and still undescribed species of the cycliophorans phylum loricifera been found on the mouth appendages of other lobsters such as Phylum loricifera gammarus Europe and H.
So far the cycliophorans have only been found on marine decapods from the Northern hemisphere.