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Within hours the formation of the shape is visible and then the individual components are developed days later. The size and shape of the operculum bone is dependent on the organism's location. For example, fresh water threespine sticklebacks form a less dense and smaller opercular series in relation to marine threespine sticklebacks.
[3] [4] Each filament contains a capillary network that provides a large surface area for exchanging oxygen and carbon dioxide. Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fish, capillary blood flows in the opposite direction to the water, causing countercurrent exchange. The ...
Sigma-C spicules have the shape of a C. [31] Dendroclones might be unique to extinct sponges [32] and are branching spicules that may take irregular forms, or may form structures with an I, Y or X shape. [33] [34] Megascleres are large spicules measuring from 60-2000 μm and often function as the main support elements in the skeleton. [35]
Osteichthyes (/ ˌ ɒ s t iː ˈ ɪ k θ iː z / ost-ee-IK-theez), [2] also known as osteichthyans or commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue.
Seawater contains more osmolytes than the fish's internal fluids, so marine fishes naturally lose water through their gills via osmosis. To regain the water, marine fishes drink large amounts of sea water while simultaneously expending energy to excrete salt through the Na + /K + -ATPase ionocytes (formerly known as mitochondrion-rich cells and ...
The outer layer of the epidermis (outer skin) consists of: sensory cells; cells that secrete mucus, which protects the body; and interstitial cells, which can transform into other types of cell. In specialized parts of the body, the outer layer also contains colloblasts , found along the surface of tentacles and used in capturing prey, or cells ...
Using three tests, researchers determined that the 780,000-year-old bones indicated that humans cooked fish before eating it, according to the study. This marks the earliest evidence that hominins ...
[21] [25] In most ciliate groups, however, the cells separate after conjugation, and both form new macronuclei from their micronuclei. [26] Conjugation and autogamy are always followed by fission. [22] In many ciliates, such as Paramecium, conjugating partners (gamonts) are similar or indistinguishable in size and shape. This is referred to as ...