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However, other fish do seem to sleep, especially when purely behavioral criteria are used to define sleep. For example, zebrafish , [ 6 ] tilapia , [ 7 ] tench , [ 8 ] brown bullhead , [ 9 ] and swell shark [ 10 ] become motionless and unresponsive at night (or by day, in the case of the swell shark); Spanish hogfish and blue-headed wrasse can ...
Sleep can follow a physiological or behavioral definition. In the physiological sense, sleep is a state characterized by reversible unconsciousness, special brainwave patterns, sporadic eye movement, loss of muscle tone (possibly with some exceptions; see below regarding the sleep of birds and of aquatic mammals), and a compensatory increase following deprivation of the state, this last known ...
The Somniosidae are a family of sharks in the order Squaliformes, commonly known as sleeper sharks. [1] The common name " sleeper shark " comes from their slow swimming, low activity level, and perceived non-aggressive nature.
The upper jaw teeth of the sleeper shark are spike-like, while the lower jaw teeth are oblique cusps and overlapping bases. This arrangement allows grasping and sawing of food too large to swallow. Pacific sleeper sharks have a short caudal fin, which allows them to store energy for fast and violent bursts of energy to catch prey. [8]
Many sharks can contract and dilate their pupils, like humans, something no teleost fish can do. Sharks have eyelids, but they do not blink because the surrounding water cleans their eyes. To protect their eyes some species have nictitating membranes. This membrane covers the eyes while hunting and when the shark is being attacked.
Shark bites are common in Volusia County, with blacktips and bull sharks mostly to blame. But the bites are rarely fatal. Here is what we know.
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The semifinals of the 12-team College Football Playoff are set, and no conference champions remain.. All four of the teams still alive in the playoff hosted games in the first round of the playoff ...