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The gills are composed of comb-like filaments, the gill lamellae, which help increase their surface area for oxygen exchange. [5] When a fish breathes, it draws in a mouthful of water at regular intervals. Then it draws the sides of its throat together, forcing the water through the gill openings, so it passes over the gills to the outside.
The shared trait of breathing via gills in bony fish and cartilaginous fish is a famous example of symplesiomorphy. Bony fish are more closely related to terrestrial vertebrates, which evolved out of a clade of bony fishes that breathe through their skin or lungs, than they are to the sharks, rays, and the other cartilaginous fish. Their kind ...
papula; also occasionally papulla, papullae), also known as dermal branchiae or skin gills, are projections of the coelom of Asteroidea that serve in respiration and waste removal. Papulae are soft, covered externally with the epidermis , and lined internally with peritoneum .
Gill openings: Usually five pairs of gill slits which are not protected by an operculum. Five pairs of gill slits protected by an operculum (a lateral flap of skin). Type of gills: Larnellibranch with long interbranchial septum: Filiform with reduced interbranchial septum Spiracles: The first gill slit usually becomes spiracles opening behind ...
The defining characteristic of a vertebrate is the vertebral column, ... (e.g. in the skin, gills, gut and gonads). Much like the mammalian immune system, ...
By this time they have undergone metamorphosis, lost their eyes and gills, developed a thicker skin and mouth tentacles, and reabsorbed their teeth. A permanent set of teeth grow through soon after birth. [124] [125] Gills are only necessarily during embryonic development, and in species that give birth the offspring is born after gill ...
Gill arches supporting the gills in a pike. Branchial arches or gill arches are a series of paired bony/cartilaginous "loops" behind the throat (pharyngeal cavity) of fish, which support the fish gills. As chordates, all vertebrate embryos develop pharyngeal arches, though the eventual fate of these arches varies between taxa.
The characteristics of adult echinoderms are the possession of a water vascular system with external tube feet and a stereom endoskeleton. Stereom is a calcareous material consisting of ossicles connected by a mesh of collagen fibres, which is unique to this phylum.