Beach Marine Life

Marine Life You May Encounter


Jellyfish catch their prey by using nematocysts, small stinging organs present in the tentacles and oral arms. The stinging cells of jellyfish are like miniature harpoons with barbs on the end that inject poison to paralyze their prey. They usually wait for small animals to swim or drift into their tentacles.

Jellyfish have no intestines, liver or pancreas which are so important in the digestion of food in most animals. Jellyfish don't produce bulky waste products, and what they do produce is passed out through their large mouth. In fact, floating animals like the Jellyfish cannot afford to carry heavy items of food in their stomach while digestion takes place, because this would increase their weight, making it more difficult to stay afloat. Therefore, the Jellyfish digest their food and get rid of the waste matter very rapidly.

Jellyfish usually drift, but occasionally you will see them swimming. Jellyfish swim by rhythmic pulsations of the umbrella or bell. The movement is very much like an umbrella being open and shut slowly. It is coordinated by a very simple nervous system and by sense organs around the edge that are sensitive to light and gravity and chemicals in the water.

Most Jellyfish use their tentacles to sting their prey, but usually it is too weak to hurt people. Although we do not see them in our waters, the Box Jellyfish is one of the most deadly jellyfish. In Australia, they kill up to 65 people a year and when a Box Jellyfish stings a person, they can die in less than three minutes.

Jellyfish don't have many enemies, but there are some animals like a Banner fish that isn't bothered by their tentacles. Turtles will eat them and certain fish and snails nibble on their tentacles.

Jellyfish have no lungs or no gills or any special breathing organs. The walls of the body and tentacles are so thin that the oxygen molecules are able to pass directly from the water into the internal organs and the carbon dioxide molecules pass out of the body in the same way. Thus, one might say that a Jellyfish breathes with its entire body.

The senses of jellyfish are limited. They have touch receptors on their tentacles and around their mouths to help capture food. These touch receptors may also detect vibrations in the water caused by the movement of a fish, crab, or other animal swimming by. They do not have a nose or tongue, but what they do have are special cells that smell and taste scattered all over their bodies. Sea jellies do not have eyes like human eyes, but many have light sensitive organs around the margins of their bodies. In most cases, these organs do not detect shapes or movement, but allow the jellyfish to tell light from dark. In order to tell up from down they sense the sunlight at the surface of the ocean.

Some research scientists are studying the chemicals in Medusa and other Jellies for possible use in treating cancer and other diseases. One of the bioluminescent chemicals found in a Medusa jelly from the Pacific Northwest has already been found to be useful in certain types of Medical research. This substance allows doctors to trace the movement of specific chemicals through the body!


When summer comes, the days are long and the beach beckons. You hop into the car anticipating the relaxing swim in the Gulf of Mexico. You park your car, lay out your blanket, position your chair and you ready yourself for the easy day ahead. You bee-line for the water and it feels great! The cares of the world wash away with each gentle move out just a bit further and WHAM!...You feel the puncture of the stingray's barb in your foot. The pain increases and you panic, the wound feels as if it is on fire and the sensation of pain is working its way up your leg. You have just encountered the "Southern Stingray" (Dasyatis americana).

This denizen of the deep is usually found in the shallow waters along our coastline and is often camouflaged in the sand. When stepped upon, the stingray strikes upwards with its tail, driving a tail spine deeply into a foot or leg. The force of this thrust has been known to penetrate a thick rubber boot.

The tail spine is located a few inches out from the base of the whip-like tail and is made of a bone-like material called "vasodentine". Along the sides of the spine are a series of sharp recurved teeth. On its underside there are grooves which contain a soft, spongy, grayish tissue that produces venom.

After a sting occurs, bleeding may be heavy and should not be stopped as it helps eliminate the venom. The area of the wound becomes swollen and intense pain develops. The pain peaks after 30 to 60 minutes and can move outward from the wound. The pain can last for up to 48 hours.

To prevent a stingray's "sting" or "bite", the stingray shuffle should be done. Instead of lifting your feet and stepping forward you simply shuffle your feet and push a little mound of sand in front of your toes as you move forward. This mound of sand will push against a stingray's body causing it to dart away.

If you are stabbed by a stingray, seek immediate medical attention! The stingray's venom breaks down when exposed to heat, so soaking the wounded area in hot water (120 degrees Fahrenheit) for at least 30 minutes, will decrease the pain and help neutralize the venom.

Ice should never be applied to the area even though some localized swelling may occur. If the stingray's barb or spine is imbedded in the wound it should not be removed unless it comes out easily. The recurved barbs can cause extensive damage if forcefully removed.

A victim's condition may deteriorate rapidly so it is important to get to a hospital or medical facility as quickly as possible. A doctor can then determine whether there is a need for a tetanus shot or any further treatment.

Portuguese Man Of War

You arrive at the beach and see little bluish-purple balloons and you wonder, "What are they?". You have just met the Portuguese Man Of War or "Blue-Bottle". Most of us mistake it for a jellyfish, but it is not. As a matter of fact, it isn't even a single animal, it is a "colony" of organism working together in order to survive. The Portuguese Man Of War is actually a "siphonophore" and is made up of four separate "polyps".

This venomous creature got its name from the "air-filled balloon" that sits on top of the water surface. This balloon looks like an old sailing ship at full sail.

The man-of-wars second organism is its tentacles. They are long, thin tendrils that can reach downward almost 165 feet into the ocean, though most commonly are seen measuring 30 feet They are covered in venom-filled nematocysts used to paralyze and kill fish and other small creatures. For humans, a man-of-war sting is excruciatingly painful, but rarely deadly. But beware—even dead man-of-wars washed up on shore can deliver a sting.

Muscles in the tentacles draw prey up to a polyp containing the gastrozooids or digestive organisms. A fourth polyp contains the reproductive organisms.

Man-of-wars are found, sometimes in groups of 1,000 or more, floating in warm waters throughout the world's oceans. They have no independent means of propulsion and either drift on the currents or catch the wind with their pneumatophores. To avoid threats on the surface, they can deflate their air bags and briefly submerge.

Size: Float, 12 in (30 cm) long, 5 in (12.7 cm) wide; tentacles, up to 165 ft (50 m) long
Did you know? The tiny Nomeus gronovii fish is immune to the sting of the Portuguese man-of-war. It lives among the tentacles and even snacks on the stinging tendrils.

Bottle-nose Dolphins

These mammals regularly cruise our coastline and waterways, frolicking and feeding and are frequently mistaken as sharks by unaccustomed patrons.

In the wild, dolphin are capable of reaching speeds of nearly 20 miles an hour. They come to the surface to breathe about two or three times a minute. They travel groups and communicate with each other by a system of squeaks and whistles. Pods or Schools have been known to come to the aid of another dolphin, which is injured, and help it to the surface.

Bottlenose dolphins can track or locate prey by the use of echolocation. They can make up to 1,000 clicking noises per second. The sounds travel until they “hit” an object or objects and then bounce back to the dolphin; this tells the dolphin the location, size, and shape of the object or prey.

Their diet consists mainly of bottom-dwelling fish and also eat shrimp and squid. They also can be seen following fishing boats, hoping for leftovers. Dolphins are threatened by commercial fishing for tuna, since they can become entangled in nets and other fishing equipment, are unable to surface for air and drown.

They live about 45 to 50 years in the wild. Dolphins can grow from 10 to 14 feet in length and weigh in at upwards of 1,100 pounds. They are also capable of jumping (breaching) up to 16 feet out of the water!


Manatees (or Sea Cows) are often seen in coastal waters and rivers, poking along in the shallows, slowly feeding. Though they are normally quite docile, they should not be approached. They move at a slow pace, which lends credence to the comparison of a "sea cow", but the similarity ends there! If you put aside their massive body size, you will see they are graceful swimmers, propelling themselves with a strong tail that is capable of allowing them to glide along at a steady 5 miles an hour, but can hit bursts of 15 miles an hour in the event they need to.

You may catch a glimpse of these graceful animals swimming alone, in pairs, or in small groups of a half dozen or less. They can be seen from the shore or by boat, but a trained eye is required, since the manatee's nose and nostrils are often the only thing visible above the water's surface. Like all marine mammals, they must breathe air at the surface. Resting manatees can stay submerged for nearly 15 minutes or so, but they have to surface every three or four minutes when they are actively swimming.

Manatees, after they are born, can typically swim on their own within an hour! Their mothers must help them up to the surface in order to take their first breath. Manatee calves drink their mothers' milk, but adults eat water grasses, weeds, and algae—and lots of it! These gentle giants can eat a tenth of its own massive weight in just 24 hours. They can live up to 40 years in the wild and weigh in anywhere from 440 to 1,300 pounds. They can reach lengths of 8 to 13 feet.

Today, manatees are endangered and even though they are protected by law, these incredible animals still face threats. They are often hit by motorboat propellers, especially with the increase in pleasure boating. If you get a chance to see a manatee close up, you will see the prop scars on their body, often as open wounds. The other threat that faces most marine mammals is the chance of becoming entangled in fishing nets.

Sea Turtles

A less common site along the coast are also several species of marine turtles, among these the Loggerhead, Green Turtle, Hawks Bill, and the Atlantic Ridley. Loggerheads are commonly seen in along our coastline and are the most abundant marine turtle species in the waters of the United States. Problems surrounding declines of this species is mainly due to pollution, shrimp trawling, housing and beach-front development in their nesting areas. They have been on the threatened species list since 1978.

They have a huge range that encompasses almost all of the world's oceans except the most frigid. Though they seem to prefer coastal habitats, they are often found in inland waterways and, amazingly, travel hundreds of miles out to sea.

Loggerheads have massive heads and strong jaws. Adult males can reach about three feet in shell length alone. They can weigh upwards of 250 pounds and large sea turtle specimens have been found, weighing more than 1,000 pounds.

Primarily, they are carnivores. Their diet consists of jellyfish (yes, they eat jellyfish), conchs, crabs, and even fish, but are also found eating seaweed and sargassum on occasion. They live to be more than 50 years old, can grow to a length of 3 feet and can reach speeds of 15 miles per hour.

The mature females can be found returning to the beach where they were hatched, in order to lay their eggs. Her effort to reach that beach is incredible! They have satellite tracking models that show long, ocean swims over thousands of miles! Although population numbers of turtles around the world are unknown, scientists are seeing marked decreases even with the endangered species protection acts that are in place.