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The epidermis is either a syncytium or a single layer of cells, and is covered by a thick collagenous cuticle. The cuticle is often of a complex structure and may have two or three distinct layers. Underneath the epidermis lies a layer of longitudinal muscle cells. The relatively rigid cuticle works with the muscles to create a hydroskeleton ...
An example of a pseudocoelomate is the roundworm. Pseudocoelomate animals are also referred to as blastocoelomate. Acoelomate animals, like flatworms, have no body cavity at all. Semi-solid mesodermal tissues between the gut and body wall hold their organs in place.
Ascaris is a nematode genus of parasitic worms known as the "small intestinal roundworms". [1] One species, Ascaris lumbricoides , affects humans and causes the disease ascariasis . Another species, Ascaris suum , typically infects pigs .
Ascaris lumbricoides is a large parasitic roundworm of the genus Ascaris. It is the most common parasitic worm in humans. [1] An estimated 807 million–1.2 billion people are infected with Ascaris lumbricoides worldwide. [2]
Whole blood with microfilaria worm, giemsa stain. L. loa worms have a simple structure consisting of a head (which lacks lips), a body, and a blunt tail. The outer body of the worm is composed of a cuticle with three main layers made up of collagen and other compounds which aid in protecting the nematodes while they are inside the digestive system of their host.
The sensors are primarily single cells that detect light, chemicals, pressure waves and contact, and are present on the head, appendages (if any) and other parts of the body. [8] Nuchal ("on the neck") organs are paired, ciliated structures found only in polychaetes, and are thought to be chemosensors . [ 23 ]
The body covering is a proteinaceous layer named cuticle. The anterior end is the mouth with distinct lips, and the anus opens towards the posterior. They are diecious with marked sexual dimorphism. Males are shorter and smaller, with straight blunt tails, while females are bigger and longer, with curved tails. They all exhibit direct lifecycles.
Before Aguinaldo's Ecdysozoa proposal, one of the prevailing theories for the evolution of the bilateral animals was based on the morphology of their body cavities. There were three types, or grades of organization: the Acoelomata (no coelom ), the Pseudocoelomata (partial coelom), and the Eucoelomata (true coelom ).