10 Longest Animals in the Ocean

1. Lion's Mane Jellyfish

Tentacle length: 36.6 m. (120 ft.)

Cyanea capillata (Lion's Mane Jellyfish) is a species of cnidarians in the family Cyaneidae. They are native to Atlantic Ocean and Pacific Ocean. They are carnivores. Individuals can grow to 49.57 cm. They have sexual reproduction.

The lion's mane jellyfish uses its stinging tentacles to capture, pull in, and eat prey such as fish, sea creatures, and smaller jellyfish.


The Lion's Mane Jellyfish is found in the cooler regions of the Atlantic, Pacific, North Sea, and Baltic Sea. They are especially common along the East coast of Britain. They are found in the pelagic zone as medusae and then benthic zone as polyps. (Grzimek 1972, Nichols 1979) 


Jellyfish are composed of 94% water and are radially symmetrical. It is dibloblastic, which means that it has two tissue layers. This member of the giant jellyfish has a hemispherical bell with scalloped edges. The bell is divided into eight obvious lobes by eight indentations with second order indentations. Some lobes contain sense organs including odor pits, balance organs, and simple light receptors. Its bell normally ranges in diameter from 30 to 80 cm, with some individuals growing up to a maximum of 180 cm. The oral arms are purple with reddish or yellow tentacles, hence the common name "Lion's Mane". The bell may be pink to reddish-gold or brownish-violet. The jellyfish has no fringing tentacles around the edge of its bell, but it has eight groups of 150 tentacles each on the underside of its umbrella. These tentacles contain very effective nematocysts, as does the upper surface of the jellyfish. (Banister and Campbell 1985, Grzimek 1972, Nichols 1979, Stachowitsch 1992)

2. Blue Whale

Length: 33 m. (108.27 ft.)

Balaenoptera musculus (Blue Whale) is a species of mammals in the family rorquals. They are listed as endangered by COSEWIC and in cites appendix i. They are native to Arctic Ocean, Pacific Ocean, Indian Ocean, and Atlantic Ocean. They are solitary carnivores. Individuals are known to live for 1320 months and can grow to 30480 mm. Reproduction is viviparous and dioecious. They have parental care (female provides care).

Lifespan, longevity, and ageing

Maximum longevity: 110 years (wild) Observations: The blue whale is the largest animal on earth. Its gestation period is short when considering its size. One possible explanation is that longer gestation periods would mean that the young would be born in the season spent in cold waters (Ronald Nowak 1999). It is estimated that these animals live over 100 years.


Blue whales have the lowest voices of any whale, vocalizing as low as 14 Hz at volumes up to 200 decibels. Sounds at this frequency and intensity can travel for thousands of miles in the deep ocean. These sounds may be used to communicate with other whales. Low frequency pulses may be used to navigate by creating a sonic image of distant oceanic features.

Little is known about intraspecific communication in these whales. Vision and smell are limited, but hearing is sensitive.

3. Sperm Whale

Length: 24 m. (78.74 ft.)

The sperm whale (Physeter macrocephalus) or cachalot is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus Physeter and one of three extant species in the sperm whale family, along with the pygmy sperm whale and dwarf sperm whale of the genus Kogia.

They are associated with freshwater habitat. They are native to Arctic Ocean, Pacific Ocean, Indian Ocean, and Atlantic Ocean. They are omnivores. Individuals are known to live for 924 months and can grow to 12175.38 mm. Reproduction is viviparous and dioecious.


Sperm whales swim through deep waters to depths of 2 miles, apparently limited in depth only by the time it takes to swim down and back to the surface. Their distributions are depend upon season and sexual/social status, however they are most likely to be found in waters inhabited by squid- at least 1,000 m deep and with cold-water upswellings. Because they are so well-adapted for deep water swimming, they are in real danger of stranding when they move inshore.

4. Whale Shark

Length: 18.8 m. (61.68 ft.)

Rhincodon typus (Whale Shark) is a species of modern sharks in the family whale sharks. They are associated with freshwater habitat. They are native to Asia, Ethiopia, Indian Ocean, Pacific Ocean, Atlantic Ocean, and Australia. They are solitary, diurnal carnivores. Individuals can grow to 2000 cm. Reproduction is dioecious. They have parental care (female provides care).

Lifespan, longevity, and ageing

Maximum longevity: 54 years (wild) Observations: Not much is known about the life history of these animals, the world's largest fish. One study estimated annual survival at 0.825. Age at maturity probably occurs at 13 to 25 years. Maximum longevity is unknown with estimates ranging from 54 years to over 100 years (Bradshaw et al. 2007).


This species prefers surface waters between 21° and 30°C. These giant zooplanktivores are usually found in coastal zones with high food productivity. Data collected from archival tags demonstrated that this species has the ability to dive to depths exceeding 1700 meters and can also tolerate temperatures as low as 7.8°C.

5. Basking Shark

Length: 12.27 m. (40.24 ft.)

Cetorhinus maximus (Basking Shark) is a species of modern sharks in the family of basking sharks. They are native to Pacific Ocean and Atlantic Ocean. They are carnivores. Individuals can grow to 1520 cm. Reproduction is ovoviviparous, iteroparous, and dioecious. They are fast moving animals.

Lifespan, longevity, and ageing

Maximum longevity: 32 years (wild)


These sharks are found at the surface of coastal waters during the summer to feed on seasonally abundant copepods which bloom in frontal areas during spring and summer, but it is thought they migrate further offshore or to deeper waters during winter.


This fish was once used for its liver oil and was thus virtually endangered for some time. It is still used in lesser amounts for fish meals and animal feed.

6. Giant Squid

Length: 12 m. (39.37 ft)

Architeuthis dux (Giant Squid) is a species of cephalopods in the family Architeuthidae. They are native to Pacific Ocean, Indian Ocean, Arctic Ocean, and Atlantic Ocean. Individuals can grow to 1084 mm.

Geographic Range

Giant squids are distributed in all the oceans of the world, usually in association with continental and island slopes. Concentrations of species found range from the North Atlantic Ocean, especially Newfoundland, Norway, northern British Isles and the oceanic islands of the Azores and Madeira; the South Atlantic in southern African waters; the North Pacific around Japan, and the southwestern Pacific around New Zealand and Australia; circumglobal in the Southern Ocean. Specimens are rare from tropical and high polar latitudes. (Forch 1998)


No one really knows where giant squid live because no one has seen one alive in its natural habitat. Only recent research has indicated where this habitat might be. It is in the deep sea, perhaps between 200 and 1000 meters in-depth, and it is possibly in association with the bottom of the sea rather than in mid-water. On the other hand, specimens that have been captured in nets sometimes come from mid-water.

Work done by Dr. Ole Brix, of the University of Bergen, indicated the blood of squids does not carry oxygen very well at higher temperatures. A squid will actually suffocate in warm water. Warm water will cause a giant squid to rise to the surface and not be able to get back down. So the giant squid are probably more likely to be found in cooler water. (Forch 1998) (Banister and Campbell 1985)

7. Giant Pacific Octopus

Length: 9.8 m. (32.15 ft)

The Giant Pacific octopus (Enteroctopus dofleini), also known as the North Pacific giant octopus, is a species of cephalopods in the family Enteroctopodidae. Its spatial distribution includes the coastal North Pacific, along California, Oregon, Washington, British Columbia, Alaska, Russia, Japan, and Korean Peninsula. It can be found from the intertidal zone down to 2,000 m (6,600 ft), and is best adapted to cold, oxygen-rich water. It is the largest octopus species, based on a scientific record of a 71-kg (156-lb) individual weighed live.


Giant Pacific octopuses are generally found in tidal pools and up to depths of 110 m, although they can also reside in deeper waters of up to 1,500 m. They often live in dens or lairs, under boulders, and in rock crevices. Ideal habitat for this species includes a soft substrate of mud, sand or gravel that includes large boulders for creating dens. Giant Pacific octopuses are found in greater densities near dense kelp fields. Members of this species are ectothermic, and their metabolism is dependent upon water temperature. Optimal water temperatures for giant Pacific octopuses range between 7 and 9.5 degrees Celsius.

8. Oarfish

Length: 8 m. (26.25 ft)

Regalecus glesne (Giant Oarfish) is a species of bony fishes in the family oarfishes. They are solitary carnivores. Individuals can grow to 1100 cm. They have sexual reproduction. Reproduction is iteroparous and oviparous.


The giant oarfish is found worldwide in the upper layers of the open ocean (the pelagic zone). It is believed to be oceanodromous, following its primary food source. It has been found as far north as 72°N and as far south as 52°S, but is most common in the tropics to middle latitudes. It is thought to inhabit the sunlit epipelagic to dimly lit mesopelagic zones, ranging as deeply as 1,000 m (3,300 ft) below the surface.


Little is known about oarfish behavior. It has been observed swimming by means of its dorsal fin, and also swimming in a vertical position. In 2010, scientists filmed a giant oarfish in the Gulf of Mexico swimming in the mesopelagic layer, the first footage of a reliably identified R. glesne in its natural setting. The footage was caught during a survey, using an ROV in the vicinity of Thunder Horse PDQ, and shows the fish swimming in a columnar orientation, tail downward.

It feeds on krill and other small crustaceans, as well as small fish and squid. It is known to spawn from July to December. The eggs are 2.5 mm (0.1 in) large, and float near the surface until hatching. Its larvae are also observed near the surface during this season. As an adult, it is believed to be solitary.

9. Great White Shark

Length: 7 m. (22.96 ft)

Carcharodon carcharias (Great White Shark) is a species of modern sharks in the family white sharks. They are listed as endangered by COSEWIC and in cites appendix ii. They are associated with freshwater habitat. They are native to Indian Ocean, Atlantic Ocean, and Pacific Ocean. They are solitary, nocturnal carnivores. Individuals can grow to 720 cm. Reproduction is ovoviviparous, iteroparous, and dioecious. They have parental care (female provides care).

Lifespan, longevity, and ageing

Maximum longevity: 50 years (wild) Observations: Some estimates suggest these animals may live up to 50 years (Cailliet et al. 2001).


Sharks have several highly developed senses. Their primary sense is the ability to smell. They can detect a drop of blood in 100 liters of water. They also have the ability to detect electrical charges as small as 0.005 microvolts. Prey can be detected by the electrical field generated by a beating heart or gill action. Fish in hiding can also be detected this way. At feeding aggregations, such as at whale carcasses, this generally solitary species often establishes temporary social hierarchies which are based largely on size. Among similar-sized individuals, the social hierarchy is maintained through a subtle form of body language. Recent research has demonstrated that great whites are socially complex, featuring such behaviors as parallel swimming, jaw gaping, pectoral fin depression, and even splash-fights. Great white sharks are also unusual among sharks in that they sometime rais their heads out of the water, apparently to observe activity above the surface.

10. Giant Manta Ray

Length: 7 m. (22.96 ft)

Mobula birostris (Giant Manta Ray) is a species of Myliobatiformes in the family eagle rays. They are native to Atlantic Ocean, Pacific Ocean, and Indian Ocean. They are solitary carnivores. Reproduction is dioecious.

The average life span of Manta birostris is 18-20 years. The Atlantic manta ray was once thought to be aggressive and harmful to humans as sailors created myths about them. The common myth was that mantas could capsize ones boat by leaping out of the water and crashing down upon it. Another common misconception is that mantas drown swimmers by wrapping around them. They are called "devil" ray because of the cephalic fins at the front of their heads, which resemble the horns of a devil. Also fishing boats reported that Atlantic manta rays would circle about their boats for long periods of time. These mantas were probably just displaying their corralling behavior during feeding.

In the past, two other species of manta, known as the "lesser" devil rays, Manta birostris (Pacific manta ray) and Manta alfredi (Prince Alfred's manta ray) were considered separate from Manta birostris. They have since been recognized as the same species, all now called M. birostris.

The name of manta is derived from the Spanish word, meaning blanket.


Manta birostris, unlike most other rays, are found near the surface of the ocean and to depths of 120 meters. Atlantic manta rays stay closer to shore in the warmer waters where food sources are more abundant, but occasionally can be found further from shore.