Sharks and Stingrays

 Sharks and stingrays are in the same family of cartilaginous fish called the elasmobranchs. Although they look quite different they share many of the same traits. These creatures are not so scary once you learn a little bit about them. Here is some useful and interesting information about sharks and stingrays in Hawaii


Stingrays come in all shapes and sizes:

Stingrays come in all shapes and sizes and not all have singing spines. Some rays use electricity to stun their prey (or for self defense). Rays are widespread and are found in all over the ocean and also in fresh water rivers as well. Some stingrays or “Rays” like the manta ray have no stinger at all. And are totally harmless to humans. Most stingrays are peaceful and beautiful creatures that pose very little threat to humans.

Stingrays in the environment:

Stingrays like to swim some are pelagic and swim all of the time, and some like to rest on the sea floor and will bury themselves under the sand. This is one of the reasons that people accidentally tread on them. Stingrays hide order the sand to avoid predators like sharks, and also to ambush their prey. Stingrays are masters of camouflage and will be practically invisible and may only have their eyes above the sand. Stingrays are an important part of the ecosystem, and they are also valuable as a ecological attraction whether in aquariums, or for ecotourism. Divers and snorkelers enjoy watching rays and will pay to dive with them. On the Big Island in Hawaii an industry of night diving with manta rays is a booming activity that is an important part of that islands economy.

Stingray Physiology:

Stingrays are unique in that they have a flattened body shape. This allows them to live on the seafloor and also allows them to have a unique form of locomotion, they swim by undulating their wings (called flaps). They are beautiful swimmers. Stingrays are closely related to sharks, they are fish, so they breathe water, and they have a varied diet depending on their species and their biological niche. One notable fact is that stingrays mouths are on their undersides, and their eyes are located on their upper sides, so stingrays cannot see their mouths or see what they are eating. However the  lack of vision is compensated by their array of sensory organs that allow them to locate and identify their prey. Manta rays have several differences in body design, one exception is that have their mouths on the front of their body which allows them to swim through clouds of plankton which is their food source. the second is their specialized cephalic fins that look like horns on their heads. Stingrays like sharks have highly developed senses; they might have good eyesight, great sense of smell, they have a sense of taste, They can hear, and they detect vibrations and movements in the water with a special organ called a “Lateral line”, and they can also sense electromagnetic fields and temperature gradients with a special organ called the “Ampullae of Lorenzini” . This organ is comprised of electro-receptors located around the mouth of the stingray. This extra sense may help them to detect fish and other animals hiding under the sand, or it may have another purpose as well. Most stingrays give birth to live young called pups. Most stingrays have rough skin with thousands of tiny denticles (tiny teeth like parts), and it is rough to the touch.

Stingray Products:

Stingrays have been used as food and for other products. Their flesh, skin, livers and spines have all been used is past and present times to make a array of products. Stingray spines have been used as weapons in the past because they are extremely destructive to human flesh, and have been used in spear/arrow heads, and used as daggers by native Hawaiians, as well as ceremonial cutting tools by Mayan shamans. Many products formally made from stingray can now be artificially synthesized and so demand for stingray is lessening, with the exception of the Asian medical demand for ray gill rakers. Stingrays are sometimes farmed and the skin is used as a type of leather.

What do Rays eat?:

The largest rays eat the smallest sea creatures, the manta rays can grow to a 15-20 foot wingspan, and they eat plankton, which is a collection of tiny and microscopic organisms including; invertebrates, algae, larvae and other creatures like tiny shrimp that are found in large numbers, plankton gets swept along in the ocean currents. Some of the plankton swarm together and is attracted to light. The plankton is also the same source of food for some species of whales. Animals (like manta rays) that eat plankton generally do not have teeth but are filter feeders, which tend to have strainer like organs that help then separate the plankton from the seawater. A manta ray couldn’t bite you, because he doesn’t have any teeth. Some stingrays like to eat small fish, and some will even eat Sea urchins and shellfish. And crabs. Many stingrays have a type of grinding plates for teeth that efficiently grind up spiny critters and crush hard shells.

Manta Rays:
Manta Rays are the largest member of the ray family. They can reach
over 20 foot wingspans. Mantas are filter feeders feeding on plankton they are found around the world in tropical and subtropical waters. Mantas do not have stinging tail barbs, and are harmless to humans. There are several sub species of manta ray. Mantas are endangered due to overfishing. Hawaii was the first state in the USA to ban the fishing of manta rays. Manta rays are now protected globally under international law. Manta rays have their mouths on the front of their bodies, and have triangular shaped wings (flaps), they are migratory however some individual mantas tend to congregate around coastal areas where there is a reliable food source. One example is the Kona coast on the Big Island of Hawaii where manta rays are regular visitors and resident to several bays there. Large manta rays are often accompanied by remora fish (sucker fish). Manta Rays are known to breach (jump) out of the water landing head first or tail first and even doing somersaults. Manta rays can sometimes be seen on the surface where their pectoral fins can sometimes be mistaken for shark fins. Mantas are known to visit cleaning stations on the coral reef where small fish like cleaner wrasse will clean the parasites from the larger manta ray.

Avoiding Stingrays:

Do not grab or attract stingrays with food. Handle with care is accidentally caught on a fishing line. When in stingray territory do not put your feet down on seafloor unless totally necessary. If walking along seafloor sandy bottom, shuffle your feet along to alert the stingrays so that they can swim away before you step on them. When snorkeling/diving, fan the sea floor with your fins before putting your feet down. If you get close to a stingray, do not panic or startle it. It will probably swim away.

Stingray self defense:

However several species have a sharp spine that they use for self defense. The worst thing to do to a stingray is to stand on it. They understandably want to get away from you and if necessary they will stab or slash whatever is standing on them. They presumably also use their spines to stop other creatures eating them. If you were very unlucky you could fall onto a stingray that is swimming and maybe get stung but that is very rare. Stingrays can also pose more of a threat to fishermen who catch them either deliberately or accidentally. Spear fishermen catch rays and (hopefully) eat them they just have to be extremely careful when handling the spines and the live rays. Some species of stingray have no stingers but have a electrical discharge as their self defense. These are called numb rays, and they can deliver a strong electrical shock to a would be predator, or a person unlucky enough to step on them (I have stepped on them, and it is not pleasant at all).

Electric rays:
These are known in freshwater and saltwater. These are called numb rays, and they can deliver a strong electrical shock to a would be predator, or a person unlucky enough to step on them (I have stepped on them, and it is not pleasant at all). They have a special electrical organ or pair of organs in the base of their pectoral fins, they are sluggish and tend to propel themselves with their tail instead of their pectoral fins like other rays. They can deliver a strong electrical jolt, It is with such a battery that an average electric ray may electrocute larger prey with a current of up to 30 amperes and a voltage of 50 to 200 volts, a similar effect to dropping a hair dryer into a bathtub. Electric rays have smooth flabby skin devoid of dermal denticles or spines.

Stingray Spines:

Some stingray spines are venomous. So they can deliver a very painful sting. Stingray spines can be located at the base of the tail, halfway along the tail, or at the tip if the trail depending on the species. Stingrays can sting something touching its head because they are very flexible. Some species have several spines up to 4. The spines often dislodge in the victim. the stingrays spines grow back relatively quickly.

The spines are very sharp and are barbed. The stingray spine is designed to stab and tear the victim, and cause damage. Stingray slashes can be deep. Sometimes the stingray spine breaks off in the victim. And then is difficult to dislodge because of the barbs that face backwards. A stingray spine can cause more damage as it is pulled out because of the serrated barbs. If you get stuck with a stingray barb, it is advisable to leave it in, and have a doctor remove it (this is generally true with impaling injuries with other objects as well). Keep the victim immobilized as spines can become more deeply embedded with movement.


The stingray spine can have a painful venom:

Stingrays have venom sacks near the spines inside the tissue that partially covers the spines. The stingray spine has a painful marine toxin that is more painful than venomous to humans. However every person might react differently to the poison so medical advice should be sought immediately. First aid for stingray stings is to stop bleeding, with direct pressure.  Stingray spines can severely damage vital organs. Stingrays are said to injure about 1500 people in the US each year and around the world about 17 people die from stingray stings (which is more than from shark attack).

If stung the pain can be severe lasting 1-2 hours up to 48 hours. Pain management is often necessary. Advil is sometimes used but not aspirin which may speed up the spread of toxin through the body. Take care is a pain medication is used because the victim loses sensitivity to heat and may not know when the water is too hot, and a burn could result. Have an independent person test the water before treating the victim.

Stingray FirstAid:

Then if possible soak the affected body part (usually a foot) in hot water, optimum temperature 45 degrees C (113 °F) for an adult, colder water for children may be necessary as they have more delicate skin, say 100º F/39º C.  The hot water breaks down the venom and will quickly reduce the overall pain. The water should be hot but not scalding, care must be taken to avoid burns. Advil is sometimes used but not aspirin which may speed up the spread of toxin through the body. Take care is a pain medication is used because the victim loses sensitivity to heat and may not know when the water is too hot, and a burn could result. Have an independent person test the water before treating the victim. Then off to the hospital for a few stitches, a tetanus booster shot may be necessary, and maybe some antibiotics. Severe stings may need surgery to remove the spine. Sometimes the spine breaks off or breaks up inside the wound and leaves part inside. The wound may need to be x-rayed. Deeply embedded spines or spines close to vital organs should only be removed by a doctor. If someone has signs of a severe allergic reaction, loss of consciousness or difficulty breathing call 911.


Different types of Sharks:

Sharks come in a variety of shapes sizes and colors. There are over 400 different species of sharks, and there are about 40 species found around Hawaii. Most sharks are harmless to humans. Some sharks live in the deep ocean and are rarely seen, some sharks are tiny and are less than a foot long like the Cookie cutter shark. Some of the larger sharks are known to bite people on occasion. The largest shark species is called the Whale shark, and it feeds only on plankton. Whale sharks are a favorite of divers as they are fun to swim with and may even interact with people. Whale sharks are found all around the world in tropical and sub tropical waters. There are other lesser known plankton sharks called basking sharks with very wide mouths used to scoop up plankton. Then there are large species like the Great white, Mako and Hammerhead sharks. The Great hammerhead species of shark can get quite large from 14 up to 20 feet. The largest ever reported White shark was about 26 feet long. Although larger ones surely existed in prehistoric times. Great white sharks are believed to live up to 70 years. In Hawaii there are also Galapagos sharks, Tiger sharks, Grey reef sharks, and more.

Shark Physiology:

Sharks are highly adapted to their environment and are good swimmers, and are very tough and resilient. Sharks also have highly developed senses; they can have good eyesight, great sense of smell, they have a sense of taste, which is why some species will tend to take a test bite first, and may also be why they usually spit out humans after just one taste. Sharks can hear sound (they have ears), they can detect vibrations and movement in the water with a special organ called a Lateral line, and they can also sense electromagnetic fields and temperature gradients with a special organ called the Ampullae of Lorenzini. This organ is comprised of electroreceptors located around the snout of the shark. This extra sense may help them to detect fish and other animals hiding under the sand, or it may have another purpose as well. Sharks either lay eggs or give birth to live young called pups. Some species like the great hammerhead can give birth to a litter of 55 pups at once. Sharks do not have scales like other fish. They have rough skin with thousands of tiny denticles (tiny teeth like parts), and it is rough to the touch. Shark skin has been used a sandpaper in the past, and also as a type of leather.

Reef sharks:

Probably one of the most common sharks in Hawaii that you are most likely to see is the reef shark. There are a few species of reef shark, the most common is the white tip. The white-tip is a smaller shark that likes to hang around the coral reef and rocky caves along the shoreline. They eat reef fish, and are active at night. They can swim through and crawl through caves and crevices searching for fish and critters hiding in the reef.

Reef sharks do not have to keep swimming to breathe. They can sit in one place and gulp water to pump oxygenated water over their gills. So it is common to see reef sharks sitting on the sea floor or in caves just waiting or hanging out. Some divers consider reef sharks to be safe, and will try to handle them, Eventually the shark gets annoyed and will turn around and bite someone. So do not grab any shark, unless you want to get bit.

Tiger sharks:

A common species in the Hawaiian islands (and elsewhere) is the tiger shark. The Tiger shark is called “Niuhi” in Hawaiian. The mating season for tiger sharks in Hawaii is January. Tiger sharks seem to like warmer waters. They are common to warm waters and reefy areas around the world. Tigers like cruising deeper water although they can come inshore and into shallow water if they choose. Some shark species are reputed to even take animals that are is shallow water or standing next to the water. Tiger sharks have evolved over million of years to have serrated teeth that enable them to eat sea turtles and other sea creatures found naturally in their environment. So a tiger shark will probably think that all turtles and turtle shaped objects are their food. There is now a state sponsored study in Hawaii to learn more about the behavior of tiger sharks. a sample group of about a dozen tger sharks have been tagged with GPS trackers and report their location to a database whenever they surface. This is proving very interesting to see the habits or the local tiger sharks and the range of their movement. There are almost no fences in the ocean so sharks can swim wherever they want to. Some species like the bull shark can even swim up rivers and can live indefinitely in fresh water, although freshwater sharks are not as common as saltwater sharks. It is also suggested that bull sharks are born in fresh water and then spend par of their life cycles in th ocean, perhaps returning to mate or to give birth to the next generation.

Hammer Head Sharks:

There are several species of hammerhead shark. There is a large species that grows to 14 foot that swim in the deep ocean. These are also considered to be among the “man-eaters”.

A hammerhead pup, about 12 inches long, killed by a fisherman.

People and Sharks:

People and sharks are sharing the ocean everyday mostly without incident. Most people will never see a shark in the wild in their entire lifetime. Even surfers and sailors go for decades without ever seeing a shark. Fishermen however are more likely to see them. Sharks tend to avoid people. They can swim silently by without ever being noticed or bothering anyone. The best way to see sharks in their natural state is to go scuba diving. Sharks encountered tend to go about their business and pay little or no attention to scuba divers. Unless the diver does something to attract their attention, like try to feed them. Sharks also do not spend all of their time eating. They are efficient hunters and only have to eat some of the time. They are generally opportunistic feeders, so when a meal is put right in front of them they will tend to take advantage of the opportunity. This means if there is a sick dying or dead fish in the water they will go for that rather than chasing a healthy fish around and wasting energy (but there are exceptions). We do not generally use the term “man-eaters” anymore. It is an old fashioned term used in the olden days to strike fear into the hearts of sailors and fishermen and children. It is an erroneous term because most species of sharks are scavengers and therefore capable of eating a man (Even if it is just one tiny piece at a time), and just like any other dead thing in the water long enough it usually gets cleaned up by the “scavengers” eventually. But the shark species we should be concerned with and be a little more wary of are the “person-biters”.  There are several species of sharks that are better known as people biters. These include the; Tiger, White, Mako, Bull shark and a few more. Don’t forget that all sharks can bite, it is just that bigger ones tend to do more damage. Even the lemon shark a gummy type shark species considered harmless can bite if provoked and make a mark with its super tiny teeth. Even the Cookie cutter shark will bite but it has a small mouth and can only take a golf ball size bite out of larger prey.

Human intrusion into the sharks habitat:

More people are in the ocean these days with swimming, and ocean sports and not to mention the human population explosion, so there are more people in the water these days than ever before . As you might expect this will eventually lead to an increase in shark/person encounters. Shark sightings, and occasional shark bites will become more common, and sadly a few shark related injuries and even fatalities.

Shark behavior vs. Human behavior:

Sharks were little understood and much feared in the old days. People thought of sharks as evil spirits, while other cultures thought of them as shark gods, or reincarnations of their ancestors, and made sacrifices to them. Native Hawaiians even had shark temples and had sacred places reserved for sharks. The Hawaiian word for shark is “Mano”. Nowadays we study sharks and know much more about their behavior. We know that they do not regularly interact with people, and generally avoid people. These behaviors can be altered when fishing attracts sharks to food, and places where people are. We know that sharks are good at finding food, an can be attracted by smells and vibrations in the water. Sharks also have the ability to detect electrical activity that can help them find food hidden under the sand (like rays). Sharks like to eat, so people who want to avoid sharks should stay away from their food source, and they should also not act like shark food. Sharks will come around dead or dying fish, garbage n the water, blood, and that sort of thing, anything that smells like food shark will be attracted to. Thinks that sound like dead or dying animals/fish also attract sharks. And possible things that look like their favorite foods also attract them.

The turtle is one of the favorite foods of the Tiger sharksurfclubmaui-turtle-swimming

Water Activities:

When kayaking, boating, or SUP paddle boarding do not dangle your feet or hands in the water for long periods. This is simply an unnecessary risk. Your hand/foot may look like a turtle’s fin or a seal’s tail especially when you are bobbing on the surface. The other high risk activity is fishing from your SUP/kayak/windsurf, or kite. This is a fairly recent phenomenon, however you are basically attracting “marine life” to you, and you are on a very small boat. We recommend fishing only from larger boats, and NOT from kayaks, Surfboards, SUP, Windsurf, or Kite. Fishing is a blood sport. Wounded fish give off a particular vibration that can be detected by sharks, blood too can be detected by sharks, so they will be attracted to your activity and follow your fish/bait/lure to the center of the action. Also to be considerate you should not fish in areas where other people swim or recreate. This places the other person at risk unnecessarily.

Sharks tend to prefer fish:

It seems that sharks prefer fish to people. Man is generally not on the sharks menu, unless of course that man puts himself on the menu. The people who are most likely to come into contact with sharks are therefore spear fishermen, who are swimming around with dead and dying fish (shark food). And they themselves might be mistaken for shark food, or might unwittingly be associating themselves with shark food. Spear fishermen, know not to carry dead fish on their persons. Some scuba divers think it is fun to feed fish to sharks. For the most part sharks play along and take the food, but when the food runs out the excited sharks might accidental mistake a fishy smelling hand as a piece of food and give it a nip. Sharks have a high degree of sensory sophistication; sight, smell, vibrations and electrical activity, so they can usually discern hand from fish, and can even deftly take fish off a divers belt, almost like a pick pocket. However, there are cases of mistaken identity where people or people’s body parts have been mistaken for food.

Mistaken Identity:
Most cases of shark bites are a case of mistaken identity. In certain situations sharks have mistaken a person as one of their usual foods, a surfer who looks like a shark, a diver looks like a seal etc. This is more likely to happen in low visibility conditions like in muddy water in rivers, after the rains (brown water), Low light conditions like at dawn and dusk, and at night. Sharks are then relying on their other senses to guide them to their meal, and they may get a mixed message on what is in front of them. Then they tend to bite first and ask questions later. Some people describes sharks as taking a test bite first. Sharks bite surfboards, kayaks, and even boats, first as if testing what they are made of. They have a good sense of taste and then they can decide if they want to have a second bite. Most shark bites are singular and it is theorized that sharks don’t like the taste of people, or that they think we are different from the fish theory are used to. Sadly this one test-bite is enough to cause a fatal injury in some cases like with bites from the larger shark species. The best way to avoid being mistaken for shark food is to avoid murky water, avoid rain runoff, and low light conditions, and also avoid looking like a meal in any way. Other shark senses can get confused like their electrical-receptors, and they have been observed biting metal objects. This could be due to the electro magnetic fields of a metallic object. It has been noted that sharks are more curious and aggressive towards divers inside metal shark cages than they are to divers outside them. There is a product that is said to repel sharks by using a electrical signal, these devices have become popular and sell for around 400 USD, however there is no hard evidence that they really work. shark experts in Hawaii have said that they have tested all types of devices and methods to try to repel sharks and none have really worked. So beware of people selling shark repellants, they may only give you a false sense of security.

Avoiding sharks:

It is a good idea to avoid putting your hand near a sharks mouth. Fishermen sometimes try to remove fish hooks from sharks mouths and get bit in the process. The ungrateful shark didn’t realize that the fishermen was trying to do them a favor, and they bite as a defensive reflex. Sharks will bite defensively people who accost them or attempt to grab, restrain, or molest them. Some sharks have a high tolerance for people and people’s touch but these are wild animals who probably just want to be left alone.

There are some commonly understood advice to help people to avoid sharks.

To avoid sharks:

  • Do not swim at dawn and dusk
  • Do not swim at night
  • Do not swim alone
  • Do not swim farther from shore than you have to
  • Do not spend more time in the water than you have to
  • Do not swim where people are fishing, (near fishing boats, nets, spear fishermen, fish farms etc).
  • Do not swim after the rains
  • Avoid swimming in river mouths and near streams, especially after it rains
  • Avoid dirty/murky water
  • Do not swim with seals, or other shark foods

When swimming:

  • Do not splash excessively
  • Do not act like you are being bit by a shark
  • Do not panic
  • Do not pee in the water or your wetsuit.
  • Do not swim if you are cut (or bleeding in any way)

When you see a shark:

  • Do not swim if you know sharks are present.
  • If you are swimming/sailing/surfing and see a shark, return to shore.
  • Do not panic, swim calmly to shore and keep your eye on the shark.
  • Tell other people you saw a shark so that they may avoid it too.
  • Tell the lifeguard/ranger etc.

If you get bit by a shark (very unlikely):

  • Stop blood loss ASAP.
  • Apply directly pressure.
  • If necessary apply a tourniquet above the wound to stop blood loss.
  • Get victim to shore ASAP.
  • Call ambulance (in USA call 9-1-1)

Shark Interactions:

Many people believe that shark petting, shark feeding, and shark diving should be banned. The thinking goes, that sharks have a natural fear of humans, and will avoid people where possible. This is a good thing. However when people start feeding sharks, doing shark cage dives, start petting sharks, and even riding sharks, then these individual sharks become accustomed to people and lose their natural fear, then they may more readily seek out people, for food/or whatever. People too may become desensitized and lose their natural fear of the shark. This is actually better in general for the sharks, but might prove to be a bad idea for the individual people.

Shark deaths:

Of course sharks have more to fear from us than we have to fear of them. People kill over 90 million sharks per year. Conservative estimate is about 10million Sharks are accidentally caught each year as “by-catch” and thrown away. Each year about 12 people are killed by sharks worldwide. By comparison, about 150 people a year die from falling coconuts.


One terrible thing that humans do to sharks is kill them for their fins. Some Asian cultures use shark fins in soup. The demand is so high that they kill an entire shark just to have its fins. Shark finning is a barbaric act and sharks are hooked and their fins cut off while they are still alive and their living mutilated bodies are thrown back into the water. What a shame to kill a beautiful creature just for its fins. Many people and many countries are outraged by this practice and have banned shark finning in their territorial waters. Hawaii is also one place where shark finning is banned.

Shark Eaters:

Many people eat sharks, and many people do not realize that they are eating sharks. Shark meat is cheap and it is often sold under fake names. Many people eat fried and battered shark meat in fish and chips. Not many are aware of this practice. Some people eat smoked shark meat, and some eat a fermented meat and rotten shark meat is a delicacy in Greenland.

People are shark eaters (unless of course they are vegetarian). Sharks are also used in other products like shark cartilage tablets for arthritis, and shark oil (liver oil) in vitamin supplements, (although this can be synthesized nowadays anyway.).

Shark Meat:

Some types of shark meat are eaten, others are poisonous unless specially prepared. Some shark meat contains high levels of urea and has a strong ammonia like taste. Sharks can also accumulate high levels of mercury and can be unhealthy of eaten in large quantities. People do not always know they are eating shark,. There are many names that shark meat is sold under for example :

Flake, Huss, Dogfish, Catfish, Grayfish, Steakfish, Whitefish, Lemon Fish, Moki, Cape Steak, Rock Salmon, Smoked Rock Salmon, Smoked Dogfish, Rigg, Gummy, Sea Ham, Sokomoro, Tofu Shark, Ocean Fillet, Surimi (Imitation Crab Meat) , Pollock, another common fish used in Imitation Crab Meat is ~not~ shark).  

List of Shark meat names from:,

Links to more information:

Call 911 if the person has symptoms of a severe allergic reaction, such as:

  • Difficulty breathing
  • Tightness in throat
  • Itching
  • Nausea
  • Fast pulse
  • Dizziness
  • Loss of consciousness

Sharks and Stingrays, by David Dorn This article was written by David Dorn, David is an avid scuba diver, first aid instructor, and water sportsman of over 30 years. David has had a lifelong fascination and respect for sharks and other sea creatures. See other articles by David Dorn on this and other websites.