So I asked leading shark ethologist and behaviourist, Professor Samuel 'doc' Gruber to elaborate. After pointing out how much pain women feel when they give birth, making the point that suffering has no effect on reproduction, he reminded me that sharks evolved their mating behaviours and the physical structures involved, separately from other animals.
Researchers have discovered that the tiger sharks in the Atlantic are genetically different from the ones in the Indo-Pacific Ocean, according to a study published in the Journal of Heredity on 10 August 2021.
The great white shark (Carcharodon carcharias) is undeniably the most well known of the ocean’s many predators. It has, one could say, “form” and is widely considered as a ruthless and terrifying man-eater, which has taken the lives of many innocent swimmers, surfers and divers.
However, it is still unclear if the presence of a single neonate ('newborn'—ed) is an isolated event or evidence that the species is using the island for reproduction.
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Since at least the 1970s, researchers have suspected that the elasmobranchs—a group of fish containing sharks, rays, skates, and sawfish—can detect magnetic fields. But up till now, no one had shown that sharks use the fields to locate themselves or navigate.
By exposing sharks to certain magnetic cue, researchers from Florida State University have now managed to demonstrate not only that sharks have an ability to detect Earth’s magnetic field but moreover that they are able to use it to travel long distances with accuracy.
Shark fishing was completely banned in the Maldives in 2010 so when the country announced plans to discuss legalising the practice again, it created a massive backlash from the international community.
Sharks have always been a valuable tourist attraction in the small island nation and the declining status of shark fisheries, exacerbated by unresolved conflicts with other stakeholders led to the declaration of total shark fishing ban in 2010. With the shark fishing ban in place, sharks are now caught as bycatch in the Maldivian fisheries.
Researchers conclude the northward range shift demonstrates water temperatures within their preferred temperature range of juvenile white sharks are becoming harder to find.
The animals have historically remained in warmer waters in the southern California Current; Between 1982 and 2013, the northernmost edge of the juveniles' range was located near Santa Barbara (34° N).
Sleep is ubiquitous across the animal kingdom but despite anecdotal reports of sleep-like behaviour in nurse sharks and other seafloor-dwelling species, the question of whether sharks actually sleep has been intensely debated but remains unknown. A key criterion for separating sleep from other quiescent states is an increased arousal threshold. True sleep is characterised by a lack of movement that can be rapidly reversed and a decreased awareness of surroundings.
Knowledge of the habitat use and migration patterns of large sharks is important for assessing the effectiveness of large predator Marine Protected Areas (MPAs), vulnerability to fisheries and environmental influences, and management of shark-human interactions.
Researchers from James Cook University's ARC Center of Excellence for Coral Reef Studies examined stomach contents of reef sharks and conducted chemical analyses of shark body tissue to find out what they had been eating.
Somewhat surprisingly after pumping sharks' stomachs to identify the contents of the last meal, the most common thing to find was in fact, nothing. "These results suggest that reef sharks eat small meals infrequently and opportunistically," Lead author, Dr Ashley Frisch said.
