A stingray is depicted with his shark friend from Little Ray & Shark Patch Things Up and displayed at 50% of viewport width.
July 2019 by V. R. Duin

FISHY FISH: WHAT ARE CARTILAGINOUS FISH?

Sometimes when we trip or fumble,
teamwork may just stop our stumble.
That's why we must always show respect
to help that comes as we least expect.
(Little Ray & Shark Patch Things Up)

Fishy Fish shows differences between stingrays and manta rays and sharks. Chondrichthyes, or cartilaginous fish, have no bones, have no swim bladders, may have no scales and may not have teeth or tongues.

Stingrays and Manta Rays and Sharks

The Elasmobranchii subclass of Chondrichthyes includes rays, sharks, skates and sawfish. These cartilaginous fish are made of cartilage. Human babies have more cartilage than adults. Over time, bone replaces some of it.


Ancient Times? Elasmobranchs date back hundreds of millions of years. Their cartilaginous endoskeletons do not fossilize like bones. Fossilized teeth show little change in their evolution over the ages.


Dating Game? Scientists use radiocarbon dating to help estimate the age of organic matter. It measures the remaining Carbon-14, or radiocarbon, a naturally-occurring radioactive isotope. Accuracy can be within decades.


From the Same Cloth? Cartilage shapes Elasmobranchs. They have no bones to provide form. Cartilage breaks and wears out. It may not repair. Distinguishing features of each Pancake Shark make them seem unrelated.

Fishy Fish Differences

In Full Bloom? Elasmobranchs may have no scales. Some species have denticles, classed as placoid scales. This tooth material with enamel coating, extends from the dermal, or middle skin layer. Electric rays have no scales.


It All Stacks Up? Denticles differ among Elasmobranchs. Fish scales grow with the fish. Denticles do not grow larger after a certain size. New ones fill the space. The pattern is regular in sharks and irregular in stingrays.


Age scales? Some fish develop scale rings each year. Counting them gives a rough aging technique. This does not work for Elasmobranchs. Measurement of calcified vertebra or fin deposits and radiocarbon dating are used.


Right Confections? Sharklet Technologies, Inc. invented denticle-like plastic medical wraps to repel germs. The CDC warns about water contamination and waterborne illness in: Healthy Pets, Healthy People.


Stop and Sink? Manta rays, Great White, Hammerhead, Mako and Whale Sharks must keep swimming. Most fish have swim bladders for up and down movement. These gas-filled sacs also may aid survival in dirty water.


Kitchen Secrets? Elasmobranchs have no swim bladders. To make up for the absence, some sharks store fats and oils in their livers. Rays and bottom-dwelling sharks have large, flat fins to control and maintain water buoyancy.


What's Inside? The largest organ, the liver, is about a third of a shark's weight. Shark livers are harvested for the medicinal trade. Predators savor them. Orcas regularly leave liver-less Great White Shark carcasses behind.


Ancestral Lungs? It is unknown if fish swim bladders evolved from ancient lungs or evolved into lungs for breathing air. Swim bladders have no ability to take in air or to extract oxygen efficiently from air.


Back from the Future? Fish breathe with gills. Before birth, people have gill-like parts. Gills are outside organs on the heads, behind the eyes of most sharks. They are under the heads of stingrays, rays and some sharks.


Gas Exchange? Few fish have to think to breathe. Exchange occurs passively and automatically as they swim. Gill muscles intake oxygen and carbon dioxide. Gases pass into the blood stream. Carbon dioxide seeps out.


Deep Breath? Sharks, stingrays and manta rays breathe differently. Sharks and manta rays draw water into their mouths, over their gills and eject it via gill slits. Stingrays and electric rays use external spiracle breathing holes.


Trademark? The large number of slit openings into the gills of Elasmobranchs is unique. Chondrichthyes have five to seven pairs of gill slits opening into one gill. Bony fish have one opening to their many gills.


Culture Club? Fish have pectoral fins. Rays use them unlike other fish. Their pectoral fins attach at the head. Rays swim with wavy motions or flap their pectoral fins like bird wings. Most fish use these fins for steering.


Master Stroke? Hammerheads swim on their sides. Most sharks, electric rays and bony fish move with caudal fins, or tail fins. The pectoral fins of angel sharks attach to the body, behind the gills, like those of other fish.


Style Awakening? Dorsal fins keep fish upright. The dorsal fin of a shark is on its back. When breaking the water surface, this triangular fin is widely recognized and respected. It is small or missing in flat rays and flat sharks.


Pair of Aces? Ventral fins are on the underside of fish. They lend balance and stability to swimming and facilitate up or down movements. They are in the pelvic area, in front of the anal fins in those species with them.


Block Chain? Sharks cannot go backwards. Unlike other fish, this kills them. Rays move elegantly, except slow, awkward electric rays. The fastest ocean swimmers may be Lamnid Sharks, per Pizard's GURPS Miscellanea.


Family Matters? Elasmobranch jaws are detached from the skull. During mating season, some male stingrays develop points on their normally dull, flat teeth. Shark's teeth vary with their dietary type. Manta rays have no teeth.


Scheduled Maintenance? Continuous tooth replacement is distinguishing. Sharks shed and replace tens of thousands of teeth over their lifetimes. Divers and beachcombers often find them. Stingray tooth findings are rare.


Yottabyte? Cookiecutter sharks simultaneously replace rows of teeth. In most sharks, new teeth move forward to fill individual gaps. Stingray teeth also push forward in bands for individual tooth replacement from behind.


On the Block? Most fish have tongue-like parts, called basihyals. Stingrays and sharks have small basihyals made of cartilage on the floors of their mouths. Osteichthyes, or bony fish, have bony basihyals.


Fringe Art? Basihyals serve no purpose in most fish. These largely immobile structures have few muscles and no taste buds. Basihyals add suction to the deep bites of cookiecutter sharks, making them an exception.


Good Taste? All fish can taste. Taste is sensed by the body surface of some fish. Catfish and saw sharks taste with whiskers, called “barbels”. Stingrays and sharks have taste buds lining their mouths and throats.


Screen Test? Bony saltwater fish drink and leak water. It enters via their mouths and gills to keep salt concentrations balanced in blood fluids. Some bony fish excrete ammonia via special pores. Others release it through gills.


Holding Forth? Stingrays and sharks neither drink nor leak water. This vital liquid comes from their food. Cartilaginous fish, mammals and amphibians convert ammonia to urea in their livers. All fish have kidneys to filter wastes.


Acid Wash? Elasmobranchs have unique urinary systems. Rays and sharks store urea. It moistens their skin. Kidneys process urea into urine. It exits through the skin. Urea makes the meat smell like ammonia, which is a base.


Extension? Fish nose holes are called nares. They provide the sense of smell. The nares of cartilaginous fish are under their bodies. Fish nares are not connected to the mouth or throat. They have no role in breathing.


Earrings? Elasmobranchs have no otoliths. Bony fish have these ring-like bones of the inner ear. Ring development matches seasonal changes. Like tree-ring dating, scientists examine and count the rings to determine age.


Sharp Note? Hearing parts are internal with no outside openings. Ear-like parts or lateral lines sense sound vibrations. Like sonar domes on vessels, echolocation or bio sonar locates and sizes up obstacles or targets.


Doubling Down? Some land and aquatic mammals echo locate. They emit sound waves to sense objects in their environment. Waves bounce back indicating relative locations. Studies show humans can learn to echo locate.


Loud and Clear? Some fish identify objects with ultrasound. These species hear at higher frequencies and over greater distances than people. Learn scientific details about What sounds can animals hear? from DOSIT.


Hidden Assets? Some animals use ultrasound to scan and navigate their environment. Ultrasound is used to create images for medical testing. With Sonography, high-frequency sound waves depict organs within a body.


View Finder? Manta rays, whale sharks and most sharks have eyes on the side. Sphyrnid Sharks, or hammerheads, have eyes at each end of hammer-shaped heads. Those of angel sharks and most rays are on top of their heads.


Love Hue? Sight requires light. Acuity varies by species and specimen. Some fish need periods of light and dark. Others live in darkness. Some are blind. Some glow to attract mates or give warning, not as light lanterns.


Glow-Getters? Bioluminescent and biofluorescent sharks glow in the dark. Bioluminescent animals emit light of their own making. Biofluorescent animals absorb light waves to cast green, red, orange or blue glows.


Bioluminescence occurs widely in marine vertebrates and invertebrates. Deep-sea viper dogfish, lantern sharks and cookiecutter sharks are marine examples. Fireflies and fungi are examples of this chemical process on land.


Biofluorescence is not self-powered. These animals absorb sunlight, then emit it as another color with a longer wavelength. Catsharks and swell sharks emit a green light. Visibility presents with low energy, producing no heat.


Amazing Powers: The speed, abilities and traits of fish motivated scientists and engineers to develop submarines, robots and water-proof equipment. Tapping into mind-blowing fish abilities benefits all human beings.