They sure do! Every living animal that consumes food has to have a way of getting rid of waste. Sharks are no different. Researchers love poop because it holds clues to what sharks eat, where they may be from and even stress levels.
To rid their stomachs of indigestible material, some sharks can force their stomachs inside-out through their mouths, wash it in sea water, then pull it back to its normal location. Shark intestines are short and compact.
After the shark digests its food in the spiral intestine and colon, what is left passes to the rectum. The poop is expelled into the sea through cloaca when it's time to release.
In fact, shark's don't pee as we know it at all. Their urine is actually absorbed by their flesh, where the urea is used to keep their scale-like dermal denticles nice and moist. The rest is simply expelled back into the water through their 'skin'.
These shades in poop come from a combination of the breakdown of blood and muscle pigments in the sharks' food, the green-colored bile that does the breaking down, and the yellow pigment bilirubin, which comes from the breakdown of the shark's own red blood cells, Dove said.
Since sharks see contrast colors, anything that is very bright against lighter or darker skin can look like a bait fish to a shark. For this reason, he suggests swimmers avoid wearing yellow, white, or even bathing suits with contrasting colors, like black and white.
Alternatively, divers and swimmers can probably reduce the chance of an interaction with a shark by avoiding bright and highly contrasting swimwear or dive gear. We personally prefer to use dark blue or black fins, mask, tank, and wetsuit while diving.
The male's sexual organ, called a “clasper” is located on the pelvic fin. Females have oviducts, a tube leading to the womb, this opening is referred to as a “cloaca”. The male will insert his clasper into the female's cloaca, releasing sperm and fertilizing her eggs.
Overall, sharks do have tongues, but they are not like the tongues of humans or other mammals. Sharks use their tongues mainly for feeding and swallowing, and they do not use them for taste in the same way that mammals do.
Some sharks such as the nurse shark have spiracles that force water across their gills allowing for stationary rest. Sharks do not sleep like humans do, but instead have active and restful periods.
One report from a site in South Carolina documents coprolites (the fancy science term for fossilized poo) of a large shark, the largest of which totaled around 5.5 inches long.
Sharks help keep the carbon cycle in motion.
When they die naturally, they sink to the seafloor, where they are eaten by scavengers.
Instead of drinking water, the shark absorbs some seawater (and salt) through its gills. A glandin the shark's digestive system gets rid of excess salt.
Natural repellents
The Pardachirus marmoratus fish (finless sole, Red Sea Moses sole) repels sharks through its secretions. The best-understood factor is pardaxin, acting as an irritant to the sharks' gills, but other chemicals have been identified as contributing to the repellent effect.
ESDs aim to overwhelm a shark's electro-sensory system. They emit electrical pulses (each one does so in a different way) that are supposed to repel the shark. So far, ESDs have been the most effective type of personal shark repellent.
Apparently, it's just a way for the sharks to cleanse their stomachs. “It's basically rinsing it out,” Skomal says. A 2005 paper describing such behavior in a Caribbean reef shark seems to confirm that, saying that sharks do this to remove “indigestible food particles, parasites or mucus.”
So, do sharks feel pain? Yes – but it is different to how we express pain . Sharks do not have the same nervous system as mammals but what we do have in common are neurons called nociceptors. These receptors are designed to detect potential harm – such as temperature and pressure.
"The results suggest that sharks can identify human body orientation, but the mechanisms used and factors affecting the nearest distance of approach remain unclear," Science News reports. Of course, sharks aren't likely to hunt you. Your chances of being attacked by a shark are astronomically small.
As in humans, the shark's inner ear also controls balance. Sharks seem to hear sounds best in the range of 20-300 Hz, and are especially attracted to irregular sounds at or below 40 Hz, which is about the range produced by struggling fish.
At that point, the male shark, the ultimate deadbeat dad, exits the story, never to be seen again. In fact, the only time a shark pup may ever meet his or her father again is if the adult tries to eat the pup. The female is left to nourish the embryos growing inside.
Shark pregnancy
Sharks typically give birth after 11–12 months of pregnancy, but some, such as the frilled shark, are pregnant for more than three years. In some sharks, a placenta develops during pregnancy.
Just like we check under our beds for monsters, sharks check for dolphins before nodding off. That's right, the toughest kids on the undersea block swim in fear of dolphins. Here, we've compiled a splash of facts to tell you why. Flexibility Gives Dolphins the Upper Fin.
As reported by Discovery Channel, the first significant discovery was that sharks hate the smell of rotting shark carcasses and quickly swim away from the scent.
Sharks are also attracted to strong movement, so swimmers should refrain from excessive splashing. 3. Fish and turtles acting erratically can be a sign of a nearby shark. 4.