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The thresher sharks have an extreme example of this tail in which the upper lobe has evolved into a weapon for stunning prey. Bottom-dwelling sharks such as catsharks and carpet sharks have tails with long upper lobes and virtually no lower lobe. The upper lobe is held at a very low angle, which sacrifices speed for maneuverability.
The shape of the hammerhead shark's head may enhance olfaction by spacing the nostrils further apart. Sharks have keen olfactory senses, located in the short duct (which is not fused, unlike bony fish) between the anterior and posterior nasal openings, with some species able to detect as little as one part per million of blood in seawater. [61]
The simpler structure is found in jawless fish, in which the cranium is represented by a trough-like basket of cartilaginous elements only partially enclosing the brain, and associated with the capsules for the inner ears and the single nostril. [9] Cartilaginous fish, such as sharks, also have simple skulls.
The head or skull includes the skull roof (a set of bones covering the brain, eyes and nostrils), the snout (from the eye to the forward-most point of the upper jaw), the operculum or gill cover (absent in sharks and jawless fish), and the cheek, which extends from the eye to the preopercle. The operculum and preopercle may or may not have spines.
And now, a new study says sharks have personalities as well. Yes, sharks. Researchers at the Marine Biological Association of the UK and the University of Exeter studied ten small groups of cat sharks
The entire body of a shark is a very efficient eating machine. Each organ has been fine-tuned for hunting and acquiring food.
Baleen whales have two blowholes positioned in a V-shape, while toothed whales have only one blowhole. [6] The blowhole of a sperm whale , a toothed whale, is located left of centre in the frontal area of the snout, and is actually its left nostril, while the right nostril lacks an opening to the surface and its nasal passage is otherwise well ...
Fish do not breathe through noses, but they do have two small holes used for smelling, which can also be referred to as nostrils (with the exception of Cyclostomi, which have just one nostril). In humans , the nasal cycle is the normal ultradian cycle of each nostril's blood vessels becoming engorged in swelling, then shrinking.