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Nails grow from a thin area called the nail matrix at an average of 1 mm per week. The lunula is the crescent-shape area at the base of the nail, lighter in color as it mixes with matrix cells. Only primates have nails. In other vertebrates, the keratinizing system at the terminus of each digit produces claws or hooves.
Amphibians are ectothermic (cold-blooded) vertebrates that do not maintain their body temperature through internal physiological processes. Their metabolic rate is low and as a result, their food and energy requirements are limited. In the adult state, they have tear ducts and movable eyelids, and most species have ears that can detect airborne ...
The largest part of it is a special structure called the valvula, which has an unusually regular architecture and receives much of its input from the electrosensory system. [66] Most species of fish and amphibians possess a lateral line system that senses pressure waves in water. One of the brain areas that receives primary input from the ...
Conversely, freshwater has less osmolytes than the fish's internal fluids. Therefore, freshwater fishes must utilize their gill ionocytes to attain ions from their environment to maintain optimal blood osmolarity. [6] [10] In some primitive bony fishes and amphibians, the larvae bear external gills, branching off from the gill arches. [11]
The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ in bony fish (but not cartilaginous fish [1]) that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift via swimming, which expends more energy. [2]
Plant anatomy or phytotomy is the general term for the study of the internal structure of plants. Originally, it included plant morphology , the description of the physical form and external structure of plants, but since the mid-20th century, plant anatomy has been considered a separate field referring only to internal plant structure.
It belongs to a lineage believed to have given rise to the three living branches of amphibians - frogs, salamanders and limbless caecilians. Creature named for Kermit the Frog offers clues on ...
Organs of plants can be divided into vegetative and reproductive. Vegetative plant organs include roots, stems, and leaves. The reproductive organs are variable. In flowering plants, they are represented by the flower, seed and fruit. [citation needed] In conifers, the organ that bears the reproductive structures is called a cone.