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An alternative model notes the extremely ancient Cambrian origins of these animals and interprets tongue worms as stem-group arthropods. [22] A recent morphological analysis recovered Pentastomida outside the arthropods, as sister group to a clade including nematodes , priapulids and similar ecdysozoan 'worm' groups. [ 23 ]
As part of the parasite defense strategy, Ascaris roundworms secrete a series of inhibitors to target digestive and immune-related host proteases, which include pepsin, trypsin, chymotrypsin/elastase, cathepsins, and metallocarboxypeptidases (MCPs). Ascaris species inhibit MCPs by releasing an enzyme known as Ascaris carboxypeptidase inhibitor ...
There may be as many as 300,000 species of parasites affecting vertebrates, [9] and as many as 300 affecting humans alone. [10] Helminths of importance in the sanitation field are the human parasites, and are classified as Nemathelminthes (nematodes) and Platyhelminthes, depending on whether they possess a round or flattened body, respectively. [8]
Halicephalobus mephisto is a species of nematode, among a number of other roundworms, discovered by geoscientists Gaetan Borgonie and Tullis Onstott in 2011. It was detected in ore recovered from deep rock fracture water in several gold mines in South Africa 0.9 km (0.56 mi), 1.3 km (0.81 mi), and 3.6 km (2.2 mi) under the surface of the Earth. [1]
Parasites can provide information about host population ecology. In fisheries biology, for example, parasite communities can be used to distinguish distinct populations of the same fish species co-inhabiting a region. Additionally, parasites possess a variety of specialized traits and life-history strategies that enable them to colonize hosts.
Plant and animal parasites have been found in samples from a broad spectrum of geological periods, including the Holocene (samples over 10,000 years old), [26] Pleistocene (over 550,000 years old), [27] Eocene (over 44 million years old), [28] Cretaceous (over 100 million years) [29] and even Lower Cambrian (over 500 million years).
Many important parasites, one large group with plastids (chloroplasts) Heterolobosea (Percolozoa) Naegleria, Acrasis: Most alternate between flagellate and amoeboid forms Jakobea: Jakoba, Reclinomonas: Free-living, sometimes loricate flagellates, with very gene-rich mitochondrial genomes Metamonada or POD: Preaxostyla: Oxymonads, Trimastix
At 8 kilometres (5 mi) across, and estimated at 100,000 years old, [3] it may be one of the largest and oldest clonal colonies on Earth. [4] [5] [6] Among animals, the largest species are all marine mammals, specifically whales. The blue whale is believed to be the largest animal to have ever lived. [7]