Ocean Sunfish

Update of post from October 26, 2013



Yes, this is a real animal. It is the ocean sunfish, an extremely large fish living in most of the world’s oceans. This fish has a nickname “head with fins” that seems very appropriate when you see what the fish looks like. It almost looks like the back half of the fish was cut off!

These fish are also weird because of how thin they are. I do not have a view of an ocean sunfish from the front, but if you were to look at one this way, it would look very skinny!

The ocean sunfish does not have scales like most fish do. Instead, they are covered by a thick, leathery skin much like sharks have. Despite this, they are not cartilaginous fish like sharks are, but they are bony fish. This is because their skeletons are made of actual bone and not cartilage.

Another nickname for this fish is “mola,” which is half of its scientific name mola mola. Unlike most fish, the mola has no tail. Instead, they have a short tail fin connected straight to the body. The word mola is a Latin word for “millstone,” which describes the circular shape the lack of a tail gives this fish.

If you look at the tail fin of the fish above, you can easily see that its tail fin is very bumpy on the back. In the picture below, the tail fin is not nearly as bumpy, merely slightly rippled on the back.

The fish pictured below is also a much different color than the one shown above. It is mostly blue instead of the gray that the other one is. Most of these fish are blue, gray, brown, or black on their body, but some have splotches of white, yellow, or even pink! The mola shown above has markings like this, but they may be algae or barnacles and not actually part of the fish’s skin.



Ocean sunfish are the largest and heaviest of all bony fish. These fish can be up to 10 feet (3.1 m) long. The only fish bigger than them are some sharks and rays, which are cartilaginous fish.

This is very large for a fish, but what is even more surprising is how tall they can be. From the top of their top fin to the bottom of their bottom fin, molas can be up to 14 feet (4.2 m) tall!

A fish this size has to weigh a lot, and this one weighs up to 5,000 pounds (2,270 kg)! This is the same as two and a half tons, which is more than most minivans weigh!

Diet and hunting

Believe it or not, ocean sunfish are somewhat similar to birds. They are almost completely different from each other, but they do have similar mouths. These fish have fused teeth, which form a sort of beak like a bird has.

The main food of molas is jellyfish, which are actually invertebrates and not fish. There are over one thousand species of jellyfish, and most of them can fall prey to these real fish. Jellyfish are known for stinging, but the ocean sunfish is protected from this by the thick layer of mucus in its throat.

Jellyfish are not the only animals these fish eat. They also consume crustaceans, mollusks, plankton, sponges, squid, and smaller fish. Ocean sunfish are not completely carnivorous as they will sometimes eat seaweed.

Habitat and range

Molas live in almost every ocean area in the world. There are a few deep sea areas that they do not inhabit, and they also don’t live in extremely cold waters. Their range still touches parts of Antarctica and goes north of Russia in some places.

Because they are so large, ocean sunfish need a lot of room to move around. Because of this, they usually do not spend their time close to the shore, though they do not swim very deep either. Most of the time, they stay above 500 feet (150 m) deep, but they have been found as low down as 1,640 feet (500 m) below the surface. It is not known if they regularly live this deep, or if they only dive down there occasionally.


Since they do not have a tail to propel themselves with, molas are very slow swimmers. They usually only move at a little over 2 miles (3.5 km) per hour! One side effect of this is that their large bodies make a great slow-moving habitat for parasites.

Now, obviously, ocean sunfish do not like having parasites on their bodies, so they have a few ways of getting them off. First of all, they will often float at the surface of the ocean and let hungry sea birds come and eat the parasites off. They sometimes let smaller fish take part in this feast as well.

The other way is a bit more out of the ordinary. Although these fish are slow swimmers, they are extremely powerful. Powerful enough, in fact, to propel themselves up to ten feet (3 m) out of the water. When they land, the violent splash landing removes some of the unwelcome guests in the fish’s skin.

Status and threats

The ocean sunfish has not been classified by any major conservation association, but they are thought to have a relatively stable population. Due to their large size, the adults do not have many natural predators, but the younger molas have a few.

There are two main natural enemies these fish face. One of them is sharks, some of the few fish larger than the ocean sunfish. The other main predator is sea lions, but these only threaten the fish in certain areas as they do not live everywhere the ocean sunfish do.

There are a few ways humans threaten these fish. Do you remember what I said the mola’s favorite food is? That’s right, jellyfish. Do you know what piece of trash closely resembles a jellyfish? Right again, – or at least I think you are right – plastic bags.

When an ocean sunfish tries to eat a plastic bag thinking it is a jellyfish, it can choke as the bag clogs its throat, or the plastic bag might clog its stomach, making it starve to death. Be thoughtful of the ocean sunfish and other ocean creatures that suffer the same way. Put your plastic bags in the trash.

These fish are also common bycatch in the fishing industry. In California, almost 30% of the catch by fishermen trying to catch swordfish is made of molas. In many other places, including places where these fish are caught on purpose, the fishing industry threatens these unique creatures.

Reproduction and young

Not much is known about the reproduction of ocean sunfish. Off the coasts of Japan, they spawn between August and October. This time period almost definitely changes based on the where the fish are.

The females carry millions of extremely tiny eggs. They are capable of making up to 300 million eggs each year! This is the most eggs of any vertebrate!

When the young sunfish hatch, they are just 0.1 inch (0.25 cm) long! Throughout their life, these babies will multiply their size by more than 60 million times! The lifespan of ocean sunfish is unknown, but one member of the same family has been known to live for more than 100 years!

Don’t forget to scroll down and comment your guess about what the next animal is!



Photo credits:

  • Ocean Sunfish – Public Domain
  • Ocean Sunfish2 – Public Domain
  • Mystery animal – Glen Fergus
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