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Springtails (Collembola) form the largest of the three lineages of modern hexapods that are no longer considered insects (the other two are the Protura and Diplura).Although the three orders are sometimes grouped together in a class called Entognatha because they have internal mouthparts, they do not appear to be any more closely related to one another than they are to all insects, which have ...
[16] [17] They have compound eyes consisting of a small number of ommatidia and three ocelli or simple eyes on the head. [18] Asymmetric mouthparts of Heliothrips. Thrips have asymmetrical mouthparts unique to the group. Unlike the Hemiptera (true bugs), the right mandible of thrips is reduced and vestigial – and in some species completely ...
The furcula is the "spring" for which the Collembola are given the name springtails. Proturans, sometimes referred to as "coneheads", do not have eyes or antennae. They possess a telson and abdominal styli thought to be vestigial legs. Diplurans have a pair of caudal cerci, from which their name, meaning "two-tailed", is derived. They also ...
The iris (brown coloured portion of the eye) controls the size of the pupil by contracting the sphincter pupillae and dilator pupillae muscles. The sphincter pupillae is the opposing muscle of the dilator pupillae. The pupil's diameter, and thus the inner border of the iris, changes size when constricting or dilating.
The human eye is a sensory organ in the visual system that reacts to visible light allowing eyesight. Other functions include maintaining the circadian rhythm, and keeping balance . Arizona Eye Model. "A" is accommodation in diopters. The eye can be considered as a living optical device. It is approximately spherical in shape, with its outer ...
Folsomia candida has an unpigmented, slender body up to 3 mm (0.1 in) in length. The head bears a pair of four-segmented antennae and a pair of post-antennal organs but no eyespots. The dorsal part of the first thoracic segment is reduced and the posterior three abdominal segments are fused. The ventral side of the fourth abdominal segment ...
Parajapygidae. Octostigmatidae. The order Diplura ("two-pronged bristletails") is one of three orders of non-insect hexapods within the class Entognatha (alongside Collembola ( springtails) and Protura ). [ 3] The name "diplura", or "two tails", refers to the characteristic pair of caudal appendages or filaments at the terminal end of the body.
Black widow spider bites. What they look like: When a black widow spider bites, it typically causes a painful pinprick sensation. The site of the bite then swells slightly and forms a red rash ...