This yr, Tiffany Haddish will host a part of Discovery’s 33rd Shark Week. She is the primary lady of colour to ever maintain the consideration. In solidarity, we at PADI caught up with the world’s prime women and non-binary shark scientists. They shared their favourite shark information and a number of the tales behind them.
1. The Historical past Of Sharks
Evolutionarily, sharks are actually previous.
“Sharks and their kin have been round for over 400 million years,” stated Lisa Whitenack of Allegheny College. “Meaning they're older than people, mammals, dinosaurs, timber and bugs!”
Catherine Macdonald, a University of Miami lecturer and the director of Field School, put this evolutionary time-frame right into a planetary scale. She stated, “Sharks have been round longer than the rings of Saturn.”
Throughout that point, sharks developed a full “vertebrate mind ‘blueprint’ made up of the key mind areas,” stated Kara Yopak. This blueprint was first seen in sharks. Ultimately, it carried by way of the remainder of vertebrate evolution all the best way to people, she stated. Yopak is a comparative neurologist with the University of North Carolina Wilmington. She investigates how brains differ inside and throughout totally different shark species.
2. Studying About Extinct Sharks From Their Tooth
Not all shark species have survived to the modern-day. In line with Jeanette Pirlo, paleontologists have discovered about many extinct sharks from their fossilized tooth. Pirlo is a Ph.D. Candidate on the University of Florida who “dabbles in shark paleontology.”
In reality, megalodons are arguably probably the most well-known extinct shark species. Additionally they have a number of the most coveted teeth. Based mostly on jaw reconstructions, megalodons are estimated to be one of many largest oceanic predators ever. The most important megalodon jaw ever rebuilt is 9 feet tall and 11 feet wide.
“C. megalodon lived for about 20 million years…and went extinct within the Pliocene,” Pirlo stated. “They have been a part of their very own evolutionary line of mega-sharks and are usually not intently associated to Nice White Sharks!”
Pirlo emphasised that it doesn't matter what common media tells you, this 20-meter shark shouldn't be hiding out someplace. It's extinct.
Three. The Secrets and techniques of Shark Intercourse
Sharks have additionally advanced actually cool reproductive efficiencies and capabilities.
For example, “sharks can reproduce each sexually and asexually. We’ve seen this documented in aquaria, the place there’s a ‘virgin start,'” stated Kady Lyons, a analysis scientist at Georgia Aquarium. She research the eco-physiology of sharks and rays.
Females of sure shark species like blacktip reef and bonnethead sharks have reproduced in captivity with out the genetic enter of males. Moreover, there was one documented case of the identical phenomena within the subject in a sawfish in Florida, Lyons stated.
Moreover, Toby Daly-Engel, director of the Shark Conservation Lab at Florida Tech University, stated, “The good factor that has come from my analysis is the concept feminine sharks are promiscuous.”
For instance, sharks share many reproductive traits with mammals, together with inner copulation (intercourse), exterior genitalia and low reproductive charges, she stated. Nonetheless, feminine sharks choose mating with a number of males over the course of 1 breeding season.
“That is opposite to the thought we’ve been bought that ladies are naturally monogamous, caretaker varieties,” Daly-Engel stated.
The shark scientist will share these and different secrets and techniques of shark intercourse with Haddish throughout Shark Week.
four. Extra About Copy — the Nitty-Gritty
For starters, male sharks have two penises referred to as claspers, Lyons informed PADI.
Misty Paig-Tran stated, “Shark claspers…even have barbs or spurs on them to carry them in place throughout copulation. Ouch.”
Moreover, feminine sharks have denticles, that are like modified tooth, on their cloacas, Paig-Tran added. She is an affiliate professor of Organic Sciences at California State University Fullerton.
“Principally, one in every of my favourite details are that shark intercourse is tremendous tough and terrible,” she joked. “I've first-hand (arm) expertise of this and ended up with ‘shark burn’ from a necropsy of a lifeless feminine 6-gill shark.”
Moreover, even after mating, sharks have advanced in distinctive methods. For example, feminine sharks of some species can retailer sperm after mating till circumstances are conducive to being pregnant and delivery, Macdonald stated. The recognized document is for 4 years!
5. What Sharks Eat
Sharks will not be the man-eating monsters of myths and movies. In actuality, they're “actually hen” and “very cautious,” stated Daly-Engel. They do a cost-benefit evaluation when approaching unknown potential prey, the scientist stated. Sharks additionally aren’t hunger-driven, she stated. They'll circle prey for a very long time regardless of if they're ravenous or in the event that they’ve simply eaten.
Moreover, what sharks do eat varies enormously by species. For instance, deep-sea Greenland sharks have been discovered with polar bear and reindeer stays of their abdomen contents, Pirlo stated. Additionally, tiger sharks, that are well-known for consuming virtually something, typically snack on migrating songbirds, Macdonald stated.
General, the preferred reality our scientists shared needed to do with the food regimen of bonnethead sharks. These are the one recognized omnivorous sharks! They eat and digest seagrass together with small fish, crustaceans and squid. It seems this predator is an omnivore, not a carnivore.
Samantha Leigh, assistant professor at California State University Dominguez Hills, found this reality. “Because of this we have to re-think the position of bonnethead sharks in seagrass meadow ecosystem dynamics,” Leigh stated.
6. Wild Shark Senses
Sharks have six senses — the identical 5 as people (odor, sight, contact, style, sound) plus electromagnetism. The latter permits sharks to sense electrical fees and magnetic fields, Jasmin Graham, President and CEO of Minorities in Shark Sciences, advised PADI.
Graham shared one other wild shark reality: whale sharks have dermal denticles, or modified tooth, on their eyeballs!
Annabel Gong, a grasp’s scholar on the University of San Diego, talked concerning the translucent nostril of the “soupfin shark.” This species additionally has an unusually lengthy migration cycle.
Lastly, Greenland sharks have a superb sense of odor. Their olfactory bulbs are among the many largest of any species and makeup one-third of their brains, stated Brynn Devine. Devine focuses on Greenland shark analysis as a postdoctoral researcher on the University of Windsor.
Coincidentally, most Greenland sharks host giant ectoparasitic copepods on their corneas. The latter may cause imaginative and prescient impairment and even blindness, Devine stated. Consequently, the species are fortunate to have such a robust sense of odor. Subsequently, they possible use this to forage and navigate all through the deep waters of the North Atlantic and Arctic Oceans, Devine stated.