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Basic characteristics of arachnids include four pairs of legs (1) and a body divided into two tagmata: the cephalothorax (2) and the abdomen (3) Almost all adult arachnids have eight legs, unlike adult insects which all have six legs. However, arachnids also have two further pairs of appendages that have become adapted for feeding, defense, and ...
The four major groups of arthropods – Chelicerata (sea spiders, horseshoe crabs and arachnids), Myriapoda (symphylans, pauropods, millipedes and centipedes), Pancrustacea (oligostracans, copepods, malacostracans, branchiopods, hexapods, etc.), and the extinct Trilobita – have heads formed of various combinations of segments, with appendages ...
Basic characteristics of arachnids include four pairs of legs (1) and a body divided into two segments: the cephalothorax (2) and the abdomen (3). The ventral side of a brown widow spider . The epigastric plates and furrow are visible, as well as the hourglass marking on the underside of the abdomen, which is a characteristic feature of widow ...
Now, however, it appears that non-orb spiders are a subgroup that evolved from orb-web spiders, and non-orb spiders have over 40% more species and are four times as abundant as orb-web spiders. Their greater success may be because sphecid wasps , which are often the dominant predators of spiders, much prefer to attack spiders that have flat webs.
The surviving marine species include the four species of xiphosurans (horseshoe crabs), and possibly the 1,300 species of pycnogonids (sea spiders), if the latter are indeed chelicerates. On the other hand, there are over 77,000 well-identified species of air-breathing chelicerates, and there may be about 500,000 unidentified species.
Sumatran orangutan (Pongo abelli) Hominoidea is a superfamily of primates. Members of this superfamily are called hominoids or apes, and include gorillas, chimpanzees, orangutans, gibbons, bonobos, and humans. Hominoidea is one of the six major groups in the order Primates. The majority are found in forests in Southeastern Asia and Equatorial Africa, with the exception of humans, which have ...
More generally, high animal diversity has a strongly protective effect against tick-borne disease. [69] Topical tick medicines may be toxic to animals and humans. The synthetic pyrethroid insecticide phenothrin in combination with the hormone analogue methoprene was a popular topical flea and tick therapy for felines. Phenothrin kills adult ...
In animals like whip scorpions and whip spiders the first two 'sternites' bearing the book lungs may actually be highly modified opisthosomal limbs. Segmentation of the opisthosoma in adult spiders is not visible, but embryo spiders typically have 13 segments, the posterior segments being called the presegmental zone.