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Caecilians have small or absent eyes, with only a single known class of photoreceptors, and their vision is limited to dark-light perception. [17] [18] Unlike other modern amphibians (frogs and salamanders) the skull is compact and solid, with few large openings between plate-like cranial bones. The snout is pointed and bullet-shaped, used to ...
The head and tail are superficially similar as the head and neck are indistinct. Unlike other snakes, the head scales resemble the body scales. The eyes are barely discernible as small dots under the head scales. The tip of the tail has a small, pointed spur. Along the body are fourteen rows of dorsal scales. Coloration ranges from charcoal ...
Spiders do not have compound eyes, but instead have several pairs of simple eyes with each pair adapted for a specific task or tasks. The principal and secondary eyes in spiders are arranged in four, or occasionally fewer, pairs. Only the principal eyes have moveable retinas. The secondary eyes have a reflector at the back of the eyes.
Compound eye of Antarctic krill as imaged by an electron microscope. A compound eye is a visual organ found in arthropods such as insects and crustaceans.It may consist of thousands of ommatidia, [1] which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color.
While most crustacean and some insect larvae possess only simple median eyes, such as the Bolwig organs of Drosophila and the naupliar eye of most crustaceans, several groups have larvae with simple or compound lateral eyes. The compound eyes of adults develop in a region of the head separate from the region in which the larval median eye ...
Paedophryne amauensis, also known as the New Guinea Amau frog, is a species of microhylid frog endemic to eastern Papua New Guinea. [2] [4] At 7.7 mm (0.30 in) in snout-to-vent length, it was once considered the world's smallest known vertebrate.
In most species, the nymphs are herbivores or detritivores, feeding on algae, diatoms or detritus, but in a few species, they are predators of chironomid and other small insect larvae and nymphs. [ 23 ] [ 24 ] Nymphs of Povilla burrow into submerged wood and can be a problem for boat owners in Asia. [ 25 ]
The relatively small eyes have movable, closable eyelids (these are fused in snakes) and round pupils. The rather short tongue is broad, bilobed and does not end in fine tips. To lick, i.e. to absorb odorous substances, slow worms have to open their mouths slightly, as they lack the gap in the upper lip that snakes possess.