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1. Manta Rays
2. Sperm Whale
3. Giant Squid
Credits and Links
Closely related to sharks is a group of fish with a skeleton made of cartilage and pectoral fins that are fused to the head region into a disc. In many species, the head is raised above the disc. Most species have a long, whip-like tail and many possess at least 1 venomous spine located along the tail. These fish are known collectively as rays.
The largest species of ray in the world – and one of the ocean’s largest fish – is the Manta Ray. These massive and mysterious fish bear a name meaning “blanket” or “cloak” in Spanish. At one point Manta Rays were sometimes called Blanket Fish.
Manta Rays are easily recognized by their diamond shape with large, triangular pectoral fins and a small dorsal fin near the base of the slender, whip-like tail. The gill slits are located on the ventral – or underside – a characteristic of rays and their relatives, the skates.
Generally, the topside of a Manta Ray is black with lighter “shoulder” patches and the underside is white with dark freckle-like spot patterns. These patterns are unique to each Manta, that can be used to identify an individual.
A signature feature of Manta Rays are two appendages on the front of their head which are rolled and projected forward while not feeding. Known as cephalic lobes, these lobes may look like horns in the animals silhouette are the reason Manta Rays are sometimes called the “devil ray.“
There are two recognized species of Manta Ray – the Reef Manta Ray and the Giant – or Oceanic – Manta Ray.
The Giant Oceanic Manta Ray is the largest of the species with a “wingspan” (also called the disk width) of up to nearly 30 feet across but most measure around 20 feet or less. The Reef Manta is smaller with an average wingspan of 10 to 15 feet.
Reef mantas are primarily found in tropical and subtropical waters of the Pacific and Indian Oceans, but may be found worldwide. They can be found in bays or reefs and seem to avoid deep, open waters.
Giant Mantas can be found in temperate, tropical and subtropical waters worldwide. They may be found offshore or out in open waters.
Each of the two species have slightly different coloration. The shoulder patches on the Giant Manta usually have a more triangular or chevron shape and the gap between them forms a “T” shape. The Reef Manta’s shoulder patches are usually more curved and the gap between may form a “Y” shape or the two patches may touch.
The area around the mouth on the Giant Manta is typically darker than the Reef Manta. The spot patterns on the Giant Manta usually clusters around the abdominal region, while the reef manta’s extend from the abdominal region and pectoral fins to between the gill slits.
The lower region of the underside of the Giant Manta’s pectoral fins is typically darker than those on the Reef Manta and the Giant Manta has remnants of a stinging spine, while this spine seems to be completely absent on the Reef Manta.
There are two known color morphs of Manta Rays: melanistic (which has an almost all black appearance) and leucistic (which appears white).
Recently the genus Manta has been has been combined with the genus Mobula – which includes their relatives the Lesser Devil Rays. Appearing much like a miniature or baby Manta Ray – the Lesser Devil Ray only reaches a wingspan of about 4 feet.
While most ray species have a mouth located on the bottom – known as an inferior mouth, Manta Rays have a mouth located on the front of their heads – this is known as a terminal mouth.
Even though they are some of the largest fish in the sea, Manta Rays feed upon some of the tiniest—zooplankton. Zooplankton consists of tiny or microscopic animals such as krill, the early life stages of larger animals like fish or weak swimmers like sea jellies—all drifting along ocean currents and tides.
Manta rays are filter feeders. The cephalic lobes unfurl to help funnel water into the manta’s mouth while it feeds. Water flows from the mouth through the gill rakers, filtering out food that is then swallowed whole. Mantas often perform graceful backflips or somersaults while feeding to pass through clusters of plankton multiple times or possibly to corral prey.
Mantas (and their relatives the Lesser Devil and Eagle Rays) have often been observed leaping clear out of the water. The full reason behind this incredible behavior is unknown. There could be multiple reasons such as it being some form of communication, to impress mates or they may perform this behavior to dislodge parasites as they are known to visit “cleaning stations” where fish such as wrasses pick off dead skin and parasites off the manta’s body. Mantas may even leap out of the water as a form of play.
Manta rays have the biggest brain-to-body ratio of any fish. Studies have suggested that mantas may be able to recognize themselves in a mirror and create “mental maps” of their environment—indicating a highly developed long-term memory.
Mantas are ovoviviparous, meaning an egg develops and hatches inside the mother. After a gestation period of about a year, the female gives birth to one or two live pups that resemble miniature adults measuring around 3 feet across. The pups are born ready to freely swim and fend for themselves since, like other rays, they receive no parental care. The estimated lifespan for manta rays is around 20, but possibly even up to 40 years.
A Manta Ray’s natural predators are large sharks and possibly Killer Whales. These gentle giants are listed as vulnerable with populations decreasing. While they can be found in warm waters worldwide, populations are sparsely distributed and highly fragmented.
Threatened by accidental by-catch, Manta Rays are also targeted for their meat, which is considered a delicacy in some countries, and for their gill rakers – which are used in traditional Asian medicine.
Several countries where Manta Rays are found have placed a fishing ban on these animals. Ecotourism, excursions to see and even swim with these gentle giants in their natural habitat, can be a great source of revenue for local economies – making Manta Rays more valuable alive than dead. Though it has been noted that Mantas that are frequently touched by swimmers may develop skin lesions due to the removal of the protective mucous layer.
Today, the AZA accredited Georgia Aquarium in Atlanta is the only aquarium in the U.S where these majestic ocean giants can be seen in person. While there is still work to be done to protect Mantas, there are rays of hope that these massive and amazing animals survive for generations to come.
Historically feared and revered in cultures around the world – the Sperm Whale is the largest toothed whale species. Easily recognized by their massive heads – the largest on the planet – and their prominent foreheads, Sperm Whales have a rectangular, box-shaped body that tapers to triangular shaped flukes that may grow approximately 16 feet from tip to tip. Male Sperm Whales may grow up to 60 feet long and weigh up to 45 tons.
Though not the largest species of whale, they possess the largest brain of any animal on Earth and they can dive deeper than almost any other marine mammal. Powerful swimmers, they are capable of cruising speeds of around 23 miles per hour.
Sperm Whales are mostly dark grey, though some have white patches on the belly – the famous 19th century novel, Moby Dick, featured an all white, mythical Sperm Whale.
While most whale’s blowholes are situated back near their eyes, the Sperm Whale’s blowhole is located toward the forward tip of their head, uniquely positioned on the left side – they are the only living cetaceans to have this particular trait.
Their heads are extremely large, accounting for about one-third of total body length. The skin just behind the head is often wrinkled. Their lower jaw is narrow and the portion of the jaw closest to the teeth is white. The interior of the mouth is often bright white as well. There are between 20 and 26 large teeth in each side of the lower jaw. The teeth in the upper jaw rarely break through the gums.
Compared to their body size, they have rather small, paddle-shaped pectoral flippers and a small, usually rounded and thick dorsal fins. They also have several small bumpy ridges that line the edge of their back from the dorsal back to to tail flukes.
In addition to their large brain, the Sperm Whale’s head also holds a large quantity of a substance called spermaceti. Scientists still do not understand the function of spermaceti – an oily fluid – one common theory is that the fluid—which hardens to wax when cold—helps the whale alter its buoyancy so it can dive deep and rise again. Spermaceti was used in oil lamps, lubricants, and candles and in addition to whale blubber, was the main reason Sperm Whales were a prime target of the commercial whaling industry from 1800 through 1987.
Their bodies are uniquely adapted for deep diving, with features such as high concentrations of the oxygen-carrying protein, myoglobin, in their muscles, and a collapsible rib cage that allows their lungs to be compressed during deep dives.
Sperm whales hunt for food during these extended dives that routinely reach depths of 2,000 feet and can last for 45 minutes. They are known to dive over 3200 feet and are capable of diving to depths of over 10,000 feet holding their breathes for over 90 minutes. After long, deep dives, individuals come to the surface to breathe and recover for approximately nine minutes.
Because sperm whales spend most of their time in deep waters, their diet consists of many larger species that also occupy the deep waters. They eat thousands of pounds of fish and squid—about one ton per day – are 3 to 3.5 percent of their body weight per day.
Female Sperm Whales almost exclusively eat squid while males may also consume other deep water and bottom dwelling creatures such as sharks, rays and fish such as cod.
But the most preferred item in the diet of any Sperm Whale is the enormous, deep sea creatures known as the Giant Squid. In what is one of nature’s largest battles between behemoths, Sperm Whales are well known for their attacks on the Giant Squid.
While the squid is able to defend itself with incredibly long arms and two tentacles and many Sperm Whales do bear scars and marks from these encounters, the whale does usually win and many large, sharp Giant Squid beaks are found in the stomachs of Sperm Whales.
Ambergris, a substance that forms around squid beaks in a whale’s stomach has historically been valued as a substance used in perfumes.
Sperm whales are often spotted in groups of 15 to 20 animals. These groups, known as pods, include females and their young, while males typically roam solo or move from group to group. Females and calves remain in tropical or subtropical waters all year long.
Sperm Whales also practice communal childcare where several females look after and take care of multiple calves – and like humans, Elephants and Killer Whales, they are one of the few mammals where females retain a matriarchal role in their society beyond their child-rearing years. Male Sperm Whales tend to migrate to higher latitudes and head back towards the equator to breed.
Calves are born after a 14-16 month gestation period, and stay with their mothers for many years. A calf will start to eat solid foods by the age of 1 year, but may continue suckling for several more years until the next calf is born. Young males will leave their female family unit at ages ranging from 4 to nearly 20 years old. These young males will often join a ‘bachelor herd’ with other males of approximately the same age and size.
Despite their size and role as a top predator themselves, Sperm Whales do have natural enemies. Killer whales have been observed attacking sperm whale pods.
Sperm whales in some parts of the world have a unique response to attacks, gathering into a formation similar to a wagon wheel – in which all members of the group position themselves with their heads in the center and their tails facing outward like the spokes of a wheel. They then fend off attack by slashing their tails back and forth. Often a vulnerable calf or injured whale is positioned at the center of this formation for added protection.
Two related species of toothed whales, the Pygmy and Dwarf Sperm Whales possess an ability similar to squids – they are able to produce a dark, ink-like liquid that helps them escape from predators. Little is known about either of these smaller Sperm Whales – both are very similar in appearance and were once considered the same species. Pygmy Sperm Whales may reach a length just over 11 feet while Dwarf Sperm Whales grow up to 9 feet long.
Despite large population drops due to whaling, sperm whales are still fairly numerous and have one of the widest global distributions of any marine mammal species. They are found in all deep oceans, from the equator to the edge of the pack ice in the Arctic and Antarctic.
Sperm whales are found in deep open waters, or around islands and coastal areas with deep canyons or very narrow continental shelves such as off the South Island of New Zealand.
Though international whaling is no longer a major threat and its population is still recovering. The sperm whale is listed as endangered under the United States Endangered Species Act.
It is said that there are few monsters left in the world. As the age of discovery began to reveal even the most remote parts of the earth, many of history’s legends and myths were exposed as previously undiscovered animals or simple exaggerations.
However one of the most undiscovered and unknown regions of the planet – the deepest parts of the world’s ocean remains a home to many creatures shrouded in mystery. One such creature has been immortalized by ancient, classic and even modern literary works.
Thought to be the source of the legendary sea monster myth – the Kraken – it is one of the largest invertebrates to ever live. The creature known as the Giant Squid.
The ocean holds an estimated 500 species of squid. Some are surprisingly tiny, only 1 inch in length but the Giant Squid may grow more than 40 feet long.
Squids are mollusks, closely related to snails, clams, slugs and of course – octopus. Squids, octopus, nautilus and cuttlefish are known as cephalopods.
Like octopus, squid have eight arms, but squids are also equipped with two long feeding tentacles that can be shot out to grasp prey. Giant squid can snatch prey up to 33 feet away by shooting out their two feeding tentacles, which are tipped with hundreds of powerful sharp-toothed suckers. These feeding tentacles are very long, often just as long as the length of the Giant Squid’s body – known as the mantle.
On the underside of the squid’s body is the funnel, a unique multipurpose tool. By pumping water and other fluids through the funnel, the squid uses it to exhale, expel waste, lay eggs, squirt ink, and move through the water by jet-propulsion. At the opposite end of the mantle are the triangular, arrowhead shaped stabilizing fins.
The mantle itself encloses the Giant Squid’s internal organs. Inside this squishy, conical shaped part of the body and different than the bulbous shape of the octopus, the squid has a tough internal shell called a “pen”. The animal’s powerful muscles attach to the pen.
Giant squid breathe using 2 large gills that rest inside their mantle cavity.
Set in the middle of the squid’s sucker-tipped arms is a sharp, stiff beak that is used to slice prey. Beyond the deadly beak is yet another appendage – a tongue-like organ known as the radula that is covered with rows of teeth that grinds the remaining bits of food.
The esophagus of the Giant Squid actually passes through the center of the animal’s brain. Oddly, the brain of a Giant Squid is shaped like a donut. Like octopus and cuttlefish, Giant Squids have very complex brains which indicate a very intelligent creature capable of problem solving and outsmarting their prey and predators.
The eyes of a Giant Squid are the largest eyes of any member of the animal kingdom. At 1 foot in diameter, these huge eyes are often described as the size of a beach ball or large dinner plate in diameter. The animals large eyes absorb more light than those found on other animals, allowing the Giant Squid to spot bioluminescent prey – or even possible predators lurking – in the dark.
Though their very name implies their large size, reports of a Giant Squid’s size are often exaggerated since finding a live giant squid is an extremely rare event. Almost everything people know about these aquatic behemoths comes from specimens washed up on beaches. Sometimes their tentacles or arms have fallen off, or have been eaten by other animals while afloat in the ocean.
Scientists often use mantle length as the best measure of a squid’s actual size. The longest mantle length on record is 7.4 feet and the longest total length (including tentacles) of a squid on record is 43 feet.
A new method for figuring out how big a squid can get includes using beak size to estimate total body length, a helpful tool considering the hard beaks are often found in the stomachs of Sperm Whales – the creature’s number one predator.
Based on this new method, scientists believe the Giant Squid could reach lengths up to 66 feet long. Giant Squids of this size would make them larger than the Colossal Squid – another enormous squid that possesses a more rounded mantle and is heavier in size but not generally as long as the Giant Squid and its two tentacles.
It is believed that Giant Squid only live about five years and, in that time, reproduce only once. Females release millions of tiny, transparent fertilized eggs into the water in a jellied clump called an egg mass. Most are quickly snatched up as food by other marine animals. But a few survive and within a few short years, grow into massive marine predators.
Based on remains found in the stomach of washed ashore Giant Squids, it is believed they mostly eat deep water fishes and other squids—including other Giant Squids.
Giant Squid are thought to swim in the ocean worldwide, based on the beaches they’ve washed upon. This distribution suggests that they prefer continental and island slopes, according to Dr. Clyde Roper – a recognized authority on the Giant Squid species.
Some researchers think there are as many as 8 species of Giant Squid but others think there is just one, with perhaps 3 subspecies.
Recent DNA studies of specimens found throughout the world and even as apart as those in Japanese and Florida waters seem to support the idea of a single Giant Squid species.
Giant Squid like creatures have long been featured on ancient maps as sea creatures and may also have been the inspiration for the legendary ship-destroying Kraken. Their encounters with Sperm Whales – the primary predator of the Giant Squid – are one of nature’s most epic confrontations. The animal’s appearance in Jules Verne’s novel “20,000 Leagues Under The Sea” have also given Giant Squids a reputation as a real-life sea monster.
Despite the Giant Squid’s legend through history, it was only in 2005 when the first underwater photographs of a live Giant Squid in its natural habitat were presented by two Japanese marine biologists. A year later video footage was acquired by the National Science Museum of Japan of a female that was lured to the surface.
Beginning in 2012, utilizing a newly developed deep water camera system and specialized lure, that minimizes disturbances to the light-sensitive creatures that live there, one of two videos captured lived Giant Squids actively hunting in water more than 2,400 feet below the surface. One video was taken in waters off of Japan, the second and most recent video from 2019 was in the Gulf Of Mexico just 100 miles southeast of New Orleans, Louisiana.
The two videos have provided great insight into the hunting tactics of these mysterious behemoths. They show that Giant Squids are active creatures and can be seen actually tracking the special lure. It was once believed that Giant Squids would simply float or hover in the water column and passively wait for food to drift by.
But the images acquired show the squid aggressively attack the baited line, revealing that though Giant Squids are not man-eating ship sinkers, these amazing animals of myth and lore are indeed quick and agile predators of its deep sea domain.
Special thanks to the following organizations for their education, research and conservation programs that provided information for this episode:
Museum Of New Zealand
Smithsonian’s Ocean Portal website
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