I’ll bet most of you reading this don’t know what the goofy word ichthyology means. Neither did I. Highlight the yellow section below to find out.
Ichthyology is the study of fish.
Category: Fish
Worst Sibling Rivalry
One species of shark is so competitive that the babies fight each other within their mother, until only one is left to be born.
Sharks almost never get cancer. Scientists are studying them to find out why, and whether their protection is adaptable to humans.
Sharks are older than trees.
Sharks have been around for roughly 450 million years, while the first trees appeared about 385 million years ago. Sharks were already swimming in ancient oceans before forests existed.
Some sharks glow in the dark.
Several deep-sea species are bioluminescent or biofluorescent, producing or manipulating light. The cookiecutter shark, for example, has a glowing underside that may help disguise its silhouette from predators below.
Sharks can replace their teeth constantly.
A shark may lose thousands of teeth during its lifetime. New teeth continually move forward from rows behind the functional teeth, creating what amounts to a conveyor belt of dental replacements.
The Greenland shark may live for centuries.
Greenland sharks are among the longest-lived vertebrates known. Scientists have estimated that some can live several hundred years, with one famous estimate suggesting an age of around 400 years.
Sharks can detect electricity.
Special organs called ampullae of Lorenzini allow sharks to detect tiny electrical fields produced by living animals. This can help them locate prey even when it is hidden beneath sand.
A shark’s skin feels like sandpaper.
Shark skin is covered with tiny tooth-like structures called dermal denticles. They make the skin rough and also help reduce drag as the shark moves through water.
Some sharks can walk.
Several species of epaulette shark can use their fins to “walk” across the seafloor and even across shallow exposed areas. They can tolerate remarkably low-oxygen conditions too.
Not all sharks need to keep swimming.
The popular idea that every shark must swim constantly to avoid suffocating is false. Some sharks, such as nurse sharks, can actively pump water over their gills while resting on the seafloor.
The whale shark is a shark, not a whale.
The whale shark is the world’s largest fish and can exceed 40 feet (12 meters). Despite its enormous size, it is a filter feeder that eats plankton and tiny organisms.
Some sharks eat plants.
The bonnethead shark, a small hammerhead relative, has been found to digest and obtain nutrients from seagrass. This makes it one of the few sharks known to have a significant omnivorous diet.
Worst Way to See Only 1/2 of the World
The flounder, a weird, flat fish, has both eyes on one side of its body.
Flounders are wonderfully bizarre fish. They look like someone took a normal fish and then decided to flatten it, rotate its face, and let it live sideways.
10 weird facts about flounders
They are born looking like normal fish.
Baby flounders start life swimming upright, with one eye on each side of their head. During development, one eye gradually migrates across the skull to the other side.
Their skull actually gets rearranged.
The eye doesn’t merely “slide” across the surface. Bones and tissues remodel as the fish develops, producing an adult whose two eyes are on the same side.
They swim sideways for their entire adult lives.
Once transformed, they settle onto the seafloor and swim with their bodies oriented horizontally rather than vertically.
They can be remarkably good at disappearing.
Many flounders can change their coloration and patterns to match the sandy, muddy, or rocky bottom beneath them. Some can even produce surprisingly elaborate patterns.
They sometimes bury themselves completely.
A flounder can wiggle its body and fins to cover itself with sand until essentially only its eyes are visible. It’s the fish equivalent of turning the lights off and pretending nobody’s home.
Both eyes can look upward.
Because both eyes are on the upper-facing side of the body, a resting flounder can watch what is happening above it while lying flat on the bottom.
They can change which side they lie on.
Although particular species usually develop with the eyes on a characteristic side, flounders as a group include both “right-eyed” and “left-eyed” species. The terminology refers to which side bears the eyes when viewed from above.
Their mouths are asymmetrical too.
The bizarre transformation isn’t confined to the eyes. The skull, jaws and other structures become adapted to a life spent lying on one side.
They can see surprisingly well despite looking half-broken.
Their upward-facing eyes are adapted for detecting prey and predators. Their vision is particularly useful for spotting movement above the seafloor.
They are ambush predators.
A flounder can remain motionless on the bottom, camouflaged and partially buried, then suddenly lunge upward and swallow a fish, shrimp, crab or other prey. The attack can be astonishingly fast considering how thoroughly un-athletic the fish looks while sitting there.
Bonus weirdness: Some flounders have been observed changing their body pattern to match different backgrounds. So their camouflage isn’t simply a fixed paint job. Their skin is more like a programmable display.
Worst Male
Some anglerfish, who live in the ocean at depths of over one mile (1.6km), have unusual lives. To see where they are going in that depth, or perhaps to attract food, the females have a chemically operated lamp that hangs on a stalk in front of their mouths. The male doesn’t need to see because early in his life, he bites into the belly of the female and stays there forever. After a while the female grows skin over the connection. The male degenerates, losing his teeth, his fins, and any manner of life beyond being a small appendage hanging off the female.
Hagfish
The hagfish has terrible table manners. It starts its meal by biting into the gill of another fish. Then it eats its way into the fish’s throat. Finally, it crawls totally inside the victim and kills and eats the fish from the inside out. These hagfish have four hearts and they all beat with independent rhythms.