Little Ray Stingray and Shark Book
July 2018 by V. R. Duin

FISHY FISH,
STINGRAYS AND SHARKS

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” expands the information in the children's book,“Little Ray & Shark Patch Things Up”, to help children compare stingrays and sharks. Adults also enjoy exploring the differences between these fish relatives.

“Little Ray & Shark Patch Things Up” is a stingray and shark book for children. Like Fishy Fish, the book helps children compare stingrays and sharks and learn the differences between these fish relatives. Stingrays and sharks are relatives with a lot in common. However, it is rare for stingrays and sharks to get along. Little Ray and the shark in his adventure work hard to develop and encourage teamwork. The illustrations and the biologically sound content in Little Ray's stingray and shark book for children make a lot of things clear about the similarities and differences in the lives of these fishy fish. The appearance and activities of electric rays and of manta rays also are distinguished from those of stingrays.

Stingrays and sharks are fish. Most fish are vertebrates. However, these rays and sharks do not have bones. Instead, they are made of cartilage. Sawfish, guitarfish and skates are in the same family as sharks and stingrays. Most fish have swim bladders that help them maintain buoyancy. Rays and sharks do not have swim bladders. Sharks use ram-ventilation to push water over their gills. Rays and some sharks sink to the bottom when not swimming. Swim bladders enable fish to move up and down in the water or maintain constant depths. This adaptation prevents them from sinking too deep or floating too high in the water. Swim bladders may also help fish survive in dirty water. Some sharks can gulp air as a primitive substitute. These sharks use their mouths for short periods to pump water over their gills to breathe while not swimming. It is an exhaustive process and cannot be maintained for long. Other sharks store fats and oils in their livers to help maintain buoyancy. Stingrays do not breathe through their mouths. Typically, stingrays are bottom feeders. They can dig trenches with their fins to locate prey under the sandy ocean floor.

Except for lungfish, which have gills and lungs, fish are characterized by the gills they use for breathing. Lungs are internal. Gills are external. Gills are located in the head area. Most rays and sharks have five pairs of gill slits, which are individual openings to gills. This structure differs from the single opening to the multiple gills in bony fish. Bony fish pump water through their mouths to their gills. Humans also develop gill-like structures during the embryonic stage. In addition to gills, stingrays and bottom dwelling sharks have openings for breathing that are like those of spiders, insects and whales. Hammerheads do not have this adaptation. Called spiracles, these openings aid in breathing while the fish is not swimming. The spiracles also may aid in identifying the presence of prey. Some sharks also have spiracles, so they can breathe while not swimming. Great White, Mako and Whale sharks do not have them, and must move to breathe.

Fish are characterized with their paired fins, which are generally used for movement through the water. Stingrays do not look or swim like sharks, or most other fish. Stingrays swim with their fins. Some stingrays move their flat, rounded bodies through the water in a wavy motion. Others flap their fins like bird wings, and soar through the water. Stingrays are elegant movers. Sharks are the only fish that cannot swim backwards. When pulled backward by their tails, their gills fill with water and they die. Electric rays tend to be slow and sluggish swimmers. Electric rays propel themselves with the movement of their tail fins. Sharks also use their tail fins to propel themselves through the water. Sharks generally cruise at a leisurely speed that shows their swimming command of the water. Hammerhead sharks swim on their sides.

Since sharks do not thrive in captivity, their speeds have not been precisely measured. In any event, stingrays and sharks in captivity have little reason to reach top speeds. Moreover, there are many different species of stingrays and sharks. As children compare stingrays and sharks, and explore the differences between these fish relatives, they learn each of these fishy fish has different swimming speeds and styles. Electric rays, catfish and eels are of interest to humans, due to their electric shock ability. The defense mechanism of electric shock is unlikely to be deadly for a healthy adult human. However, an electric ray can kill a shark. As with stingray venom, the electric charges omitted by these animals have been used throughout the ages as experimental cures and instruments of torture. However, these electric fish largely are disinterested in humans.

A stingray's mouth is under its body, as are its nostrils and gills. The eyes are on the top of the body. Although their eyesight is weak, this eye position helps stingrays keep watch while they are partially hidden in the ocean floor. This is how these fishy fish spend most of their time. Sharks spend most of their time on the move, hunting for prey. All fish have a head, with a mouth and eyes. These characteristic fish parts do not look or work alike in these animals. Not all fish have teeth in their mouths. Some fish have modified teeth in their throats to filter plankton or to grind food. Unlike the eyes of stingrays, sharks' eyes are on the sides and very useful for spotting food. A shark's mouth also is located below its skull, but it is generally larger and more destructive than that of a stingray. Electric currents can be detected by electric rays, stingrays and sharks on the prowl for hidden prey.

These fishy fish relatives have tongue-like structures, but their taste buds are located throughout their mouths. These structures are called “basihyals”. They are positioned on the floor of the mouth, but they are generally small and made of cartilage. Taste buds help stingrays and sharks decide whether to swallow prey. Taste buds are located throughout the mouths and throats of these fish relatives. Stingrays and sharks are food tasting and processing machines. These fishy fish also can vomit to rid themselves of indigestible food or to make room for the next meal. As children compare stingrays and sharks and explore the differences between them, they also learn how fish compare to and differ from other fish and people. Some bony fish have teeth on their tongues. These tongue teeth are used to hold prey or suck blood from prey. Unlike most fish, the lamprey can stick out its horny tongue.

Humans and most other land animals cannot drink saltwater. It will make them thirstier and ultimately the concentrations of salt cause deadly dehydration. Bull Sharks, River Sharks and some species of stingrays can live in fresh water. This is fortunate, because Surviving in Salt Water is complicated. Sharks and rays do not drink water like their bony fish cousins. Sea animals have developed different means of pumping or excreting excess salt back into their environment. Stingrays and sharks obtain water from their food. Water also may pass into their bodies through their gills. These fishy fish do not drink the water like other fish, because they do not leak water like other fish. To offset salt concentrations, sharks produce urea. Excess urea is discharged by a gland near the anus. The digestive systems of rays and sharks are similar.

Sharks spend most of their time on the prowl for food. Their hunts take them to shallow and deep waters. Along the way, sharks eat a variety of foods, including fish, squid, sea turtles, sea stars and mammals, be these living, dying or dead. Sharks can handle large bites and deep ocean depths. Hammerhead sharks eat stingrays. Bull sharks eat other sharks and almost anything else in the water. Like sharks, some stingrays are swimmers that hunt for small fish and other foods in the water. However, most stingrays are bottom feeders that poke around in the sand or wait for food to come their way. Stingrays are masters of ambush. The hagfish is among the most morbid of scavengers in the family of fish. It has teeth, but it does not need them to eat. The hagfish absorbs the bulk of its nutrients through its skin.

Unlike sharks, stingrays generally stay in shallow waters. Fortunately, there are plenty of fish in their hunting grounds. These fishy fish dine on snails, shrimps, crabs, worms, clams and other creatures, including fishes, stirred up from the ocean floor. The freshwater also species eat insects, including mosquitoes and their larvae. Stingrays have hard plates to crush their food. Unlike sharks, which eat dead prey and gobble up non-food objects, stingrays prefer small, fresh, live catches. However, in captivity, stingrays learn to eat processed foods. As children compare stingrays and sharks and explore the differences between these fish relatives, they also learn a lot about animal habits and survival. Electric rays are nocturnal hunters. Their days are spent hiding in the sand. However, they are ready to swim away, if needed.

The bites of a stingray are fairly mild and may not leave any marks. Electric rays also use their teeth largely for chewing food, rather than for self-defense or to attack prey or predators. The bites of a shark tend to be sharp and may not leave anything behind. A stingray might shed an occasional tooth, while crunching food with hard shells. That tooth will be replaced. As children compare stingrays and sharks and explore the differences between these fishy fish relatives, they learn lifespan of stingrays is significantly shorter and they shed far fewer teeth than their shark relatives. Stingray and shark teeth, denticles and taste buds are genetically linked to the same regenerative cells, which means they can grow more of these cells.

Sharks are in serious need of a tooth fairy, as they shed tens of thousands of teeth in their lifetimes, which can span one hundred years or more. Greenland sharks smash longevity records. The lifespans of these sharks may reach 400 years. Humans don't live long enough to count the teeth sharks shed. Sharks' teeth are longer versions of the dermal “denticles” covering their bodies. Shark teeth are arranged in rows that slowly move forward from the back of the jaw to the front. As the front teeth wear out or fall out, new rows move from behind to replace them. These shark teeth replacements happen about every two weeks. Tooth damage and replacement can be accelerated by snacking on cans, tires and other garbage that humans toss into sharks' habitat. Sharks have huge appetites.

Different sharks have different shaped teeth depending on what food they eat. Sharks that eat shellfish and crabs have flat crushing teeth. Sharks that eat fish have pointed teeth and those that sometimes eat seals and sea lions have razor sharp teeth. Some rays and sharks have sucking mouth parts instead of teeth. Stingray teeth are small and flat. Their teeth also are replaced much like sharks' teeth. There is a strong association between eating and tasting. Ancient members of this species may have had jaws that evolved into the formation of teeth. Electric rays have rows of small teeth that are sharper than those of most stingrays.

Most fish have scales for protection. Sharks and stingrays have scales that are made of the same structure as their teeth and stinging spines. The skin of electric rays is smooth and untextured. Some sharks have stinging spines, but the location is different from that of stingrays. The scales of these cartilaginous fish are called dermal “denticles”. The scales are arranged in a regular pattern in sharks and in an irregular pattern in stingrays. Shark scales feel like sandpaper to human touch. Because the bumps in sharkskin tend to repel germs, a company named Sharklet Technologies, Inc. is creating plastic wraps designed with bumpy sharkskin-like scales to fend off sources of infection in medical settings.

Unlike other types of fish scales, the scales of stingrays and sharks do not get larger as the fish grows. Instead, the fish grows more scales to fill in the larger space. In primitive times, shark skin was used as sandpaper. However, it can be hazardous to produce, so it is no longer commonly used for this purpose. If the dermal “denticles” are removed, shark skin may be used to make leather products. Unsurprisingly, the dermal “denticles” of a shark can injure prey. The skin of electric rays is soft and flabby without denticles or horns. Other fish without scales include clingfish, eels and anglerfish. Some rays are coated with a slimy mucous that reduces friction for swimming.

A few fish can live out of water for brief periods, such as eels, snakefish, climbing perch, mudskippers or walking catfish. Lungfish can survive for long periods out of the water, which is particularly helpful when their habitat goes dry. Life in the water is a characteristic of most fish. Stingrays prefer shallow waters that are near shore. They migrate to warm parts of the world. Sharks also migrate to warmer temperatures, but they are known to swim to deep, dark, cold depths. Stingrays and sharks are typically lone hunters, but they do come together for group migrations, group hunts and mating purposes. Like stingrays, sharks may come close to shore and some species cruise along the water surface. Electric rays are widely distributed from shallow waters along shorelines to oceanic waters of great depth. Like stingrays, they are largely bottom-feeders.

Since most fish are cold-blooded, they take on the temperature of their environment. A few fish can regulate their body temperature. As any swimmer or scuba diver knows, water drains body heat faster than air does. Wet suits and heated pools are used for human protection. Some sharks can raise the temperature of some body parts. Tunas also can do this to provide some protection and improve performance during deep, cold hunts. Stingrays do not have this ability, but they generally stay in warm, shallow waters. As children compare stingrays and sharks and explore the differences between these fishy fish relatives, they learn a lot about the ocean environment. The differences between these shark relatives help bust some myths about Sharks and Rays. Once rays and sharks are understood, children might want to further study electric rays, about which little is known.

Fishy Fish Comments

  • stingray and shark together admin says:

    These fish relatives can be purchased from tropical fish stores, but stingrays and sharks don't belong in the same aquarium.

  • stingray and shark book for children admin says:

    In Little Ray's book about stingrays and sharks for children, these fish relatives travel together, so children can compare them.

    • encouraging teamworkadmin says:

      Encounters with sharks generally require protective equipment and procedures encouraging teamwork.