Little Ray Stingray and Shark Book displayed at 50% of viewport width
July 2018 by V. R. Duin


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.

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. Bone replaces some of it.

Elasmobranchs are ancient. They date back hundreds of millions of years. Because their endoskeletons are made of cartilage, they do not fossilize like bony fish skeletons. Their fossilized teeth reflect little change over the ages.

Cartilage shapes Elasmobranchs. They have no bones to give them form. Cartilage breaks and wears out, but does not repair like bone. The vast difference in their appearances makes these fish seem unrelated.

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

Denticles differ among Elasmobranchs. Most fish scales grow with the fish. Denticles do not get larger after a certain size. New ones grow to fill the space. The pattern is regular in sharks and irregular in stingrays.

Denticles may repel germs. Sharklet Technologies, Inc. is creating bumpy plastic medical wraps to ward infection. The CDC warns about water contamination and waterborne illness in: Healthy Pets, Healthy People.

Manta rays, Great White, Hammerhead, Mako and Whale sharks must keep swimming. If they stop, they sink. Most fish have swim bladders for up and down movement. These gas-filled sacs may aid survival in dirty water.

Cartilaginous fish have no swim bladders. Some sharks store fats and oils in their livers to make up for the absence. Rays and bottom-dwelling sharks have large, flat fins to control and maintain water buoyancy.

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

Sharks, stingrays and manta rays breathe differently. Sharks and manta rays draw water into their mouths, over their gills and eject it through slits. Stingrays and electric rays use spiracles, external openings to breathe.

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

Fish have pectoral fins. Rays do not swim like other fish. Their pectoral fins attach at the head. Some rays swim with wavy motions. Others flap their pectoral fins like bird wings. Most fish use these fins for steering.

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 as do those of other fish. They are behind the gills.

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

Sharks cannot go backwards like other fish. Pulled this way, they suffocate and die. Rays move elegantly. Electric rays are slow, awkward exceptions. The fastest ocean swimmers may be: Lamnid Sharks in GURPS.

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

Elasmobranchs are distinguished by continuous tooth replacement. Sharks shed and replace tens of thousands of teeth during their lifetimes. Divers and beachcombers often find them with a rare stingray tooth.

Cookiecutter sharks simultaneously replace rows of teeth. In most sharks, new teeth move forward to individually fill gaps. Similarly, stingray teeth push forward in bands for individual tooth replacement from behind.

Most fish have tongues or tongue-like parts. Stingrays and sharks have small tongues made of cartilage on the floor of their mouths. Bony fish, or osteichthyes, have bony tongues called “basihyals”.

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 throughout their mouths and throats.

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.

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.

Elasmobranchs have no urinary tract. Rays and sharks store urea. It keeps their skin moist. Kidneys process urea into urine for elimination of excess urea, salts and water through their skin. Their meat smells of ammonia.

The nose holes of fish are called nares. They give fish a sense of smell. The nose holes of cartilaginous fish are under their bodies. The nares of a fish are not connected to the mouth or throat or involved in breathing.

Hearing parts are internal. Some fish have ear-like parts with no outside openings. Others sense sound vibrations with lateral lines. Like sonar domes on vessels, sound helps fish locate and size up obstacles or targets.

Fish hear frequencies that people cannot. Fish can find their way with sound. They hear sounds over great distances. Learn more from DOSIT: What sounds can animals hear?.

Manta rays, whale sharks and most sharks have eyes on the side. According to Sphyrnid Sharks in GURPS have eyes at each end of hammer-shaped heads. Those of angel sharks and most rays are on top of their heads.

Sight requires light. Acuity varies by species and specimen. Some fish need periods of light and dark. Others live in darkness and may be blind. Fish that glow may be attracting mates or giving warning.

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 cookie-cutter sharks are marine examples. Fireflies and fungi are examples of this chemical process on land.

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