The sunfishSo great) It is a bony fish that is part of the Molidae family. It is known worldwide for being the heaviest of fish, because in its adult state it could weigh 2.3 tons. Another notable feature is its rapid growth, which can be around 0.82 kg / day. This allows it to quickly reach its large body size.
So great it has a short body flattened on the sides, which ends abruptly in a substitute structure for the caudal fin, called the clavus. Their skin is thick, lacks scales, and has a silver, white, or brown coloration..
The species is native to temperate and tropical waters around the world. It tends to actively swim between the different depths of the water. In this way, it generates a particular swimming pattern, related to the time of day and the water temperature..
Jellyfish and salps make up 15% of the sunfish's diet. In addition, being a generalist predator, it consumes fish larvae, squid, small fish, crustaceans and algae..
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The sunfish is a migratory species. During the summer, it is present in the Gulf of Maine, while at the beginning of autumn it moves south, being able to go to the Gulf of Mexico or the Bahamas..
In relation to the eastern Atlantic, it migrates northeast in summer to feed on jellyfish. Later, in winter, it moves south, in search of warmer waters.
Likewise, research indicates that So great makes a migration to the vicinity of the English Channel. This mobilization coincides with the seasonal abundance in that area of salps and jellyfish.
In the Irish Sea, sunfish inhabit shallow coastal waters. However, during the winter time it is absent, which may indicate this that it migrates south, avoiding the low water temperatures at that time of year..
Although the species that make up the Molidae family may seem primitive, they are some of the last to appear within the group of fish. Thus, while these arose more than 500 million years ago, the molids originated approximately 50 million years ago..
The separation between Ramsayi cool Y So great It happened between 2.8 and 7.5 million years ago, during the time when the changes in the glaciers occurred, in the Pleistocene.
The body of this fish is large, flattened laterally. The spine is short and has fewer vertebrae relative to other fish. Although this species descends from bony ancestors, the skeleton is formed, in a high proportion, by cartilaginous tissues.
This characteristic, together with the thick layer of thin gelatinous tissue, contributes to the buoyancy of the sunfish. This constitutes a very important aspect, due to the non-existence in this species of a swim bladder..
So great It lacks a caudal fin, as a result of the degeneration suffered by the vertebral column during evolution. Instead, it has a stiff and wide lobe, called the clavus. This extends from the posterior margin of the dorsal fin to the posterior end of the anal.
In addition, it is made up of 12 rays and ends in several rounded ossicles. While swimming, the fish uses the clavus as a rudder.
The mouth is small, compared to the dimensions of its body. In this, the teeth are fused, forming a structure similar to a beak. In addition, it has pharyngeal teeth, located in its throat.
Sunfish can be up to 3.1 meters long and 4.25 meters high. Relative to weight, it is approximately 2.3 tons. Sexual dimorphism is exhibited in this species, with males being smaller than females..
The adult sunfish can have a gray, brown or white coloration. Some have mottled skin, a pattern that may be specific to each region. The coloration is usually darker dorsally, fading in a lighter tone towards the ventral area..
The skin is rough and thick, measuring up to 7.3 centimeters wide. In addition, it is made up of cross-linked collagen and lacks scales. Externally it has denticles and a layer of mucus.
Due to its large size, the shape of its body and the rapidity of its growth, the sunfish is the subject of numerous investigations. The main objective of these is to reveal the details about the genomic changes that gave rise to these characteristics.
Regarding growth, some receptor genes had a positive selection, although the development factors IGF-1 and GH do not show changes. This indicates that the GH - IGF1 axis may have played a decisive role in the body size and growth rate of this animal..
Regarding the cartilaginous skeleton, the specialists identified several genes that code for collagen, which were evolutionarily selected in a positive way. In addition, it was shown that GH - IGF1 factors have functions in regulating the development of cartilage and bones..
- Animal Kingdom.
- Subkingdom Bilateria.
- Chordate phylum.
- Vertebrate Subphilum.
- Actinopterygii superclass.
- Teleostei class.
- Superorder Acanthopterygii.
- Order Tetraodontiformes.
- Suborder Moloidei.
- Family Molidae.
- Genus Mola.
- Species So great.
IUCN has categorized the So great within the group of animals that are vulnerable to extinction. This is because its population has decreased considerably, due to various factors.
During the juvenile stage, the sunfish are constantly threatened by some larger species. For example, bluefin tuna often fiercely devour young. Also, within the group of predators are killer whales, sharks and sea lions.
In some parts of the world, such as Taiwan, Japan and Korea, the meat of the sunfish is considered a delicacy. However, in the countries of the European Union its consumption is prohibited, as it is considered a toxic and poisonous species..
Populations of So great they are vulnerable to fishing activity. This is due to the frequent accidental catch that occurs in longlines, trawl nets or gillnets..
In South Africa, trawling for Cape horse mackerel (Trachurus trachurus capensis) has caused the involuntary catch of more than 17% of moonfish annually. In California, the capture of swordfish results in between 14 and 61% of the bycatch of the So great.
This fish is protected by various laws, especially those contemplated in the countries where it lives. Thus, the Moroccan government, in 2007, approved a law that eliminates the use of driftnets.
Sunfish are distributed in the temperate and tropical waters of the Indian, Atlantic and Pacific oceans. It is also found in the North Sea and the Mediterranean.
Sightings in the North Sea and the British Isles occur during the summer, especially in the months of June and July, when the water reaches a temperature between 13 and 17 ° C.
In the eastern Pacific it lives from Canada to Chile and Peru. Also, it tends to live throughout the Indian Ocean, encompassing the Red Sea. Thus, it is located from Japan and Russia to New Zealand and Australia..
As for the eastern Atlantic, it can be seen from Scandinavia to South Africa, and occasionally in the Baltic Sea. In relation to the western Atlantic, it is found from Argentina to Canada, including the Caribbean Sea and the Gulf of Mexico.
This species prefers the open ocean, but occasionally it can enter reefs and beds of algae for the fish to eliminate its parasites..
There is a belief that the sunfish spends much of its time on the surface. However, recent research indicates that it is an epipelagic species, with a depth range of up to 400 meters. However, it can swim up to 600 meters.
The temperature of the water where it lives is above 10 ° C. If this fish stays for a long period of time in water with temperatures below 12 ° C, it can become disoriented and even die..
The adult is an active swimmer, who performs directional and horizontal movements independent of the current. In addition, it has a specific pattern of water use, according to depth levels.
Thus, during the night it is located in the warmest layer and during the day it swims vertically repeatedly between the surface and the deeper and colder waters. Although this depth range changes over time, the sunfish continues to move up and down in the water column..
Regarding behavior, the So great you can surface and “bask” in the sun. Thus, he can turn to his side and flap his fins. Researchers associate this behavior with a method of warming up the body after a dive in deep, cold water..
During these vertical movements, the search for prey can be carried out, thus being able to locate the maximum abundance of these.
Formerly it was thought that the diet of the sunfish was based exclusively on jellyfish. However, recent studies indicate that it is a generalist predator. Thus, it is able to adapt to the availability of resources offered by the environment where it lives..
Within the diet are small fish, squid, fish larvae, crustaceans, salps, mollusks and jellyfish, among which are Rhizostoma, Cyanea capillata Y Chrysaora hysoscella
It also eats sponges, small fish, flounder, cathenophores, snake starfish, Portuguese frigate birds, and eel larvae found in deep water. Regarding plant species, eat various types of eelgrass, plankton, algae and eel grass.
The wide range of foods you eat indicates that So great forages at different levels of the ocean. Thus, they do it on the surface, among floating weeds, in deep water and on the seabed.
Research works, based on the study of stomach content in young and adult species, indicate that there are differences in their diet. The diet of adult sunfish is mainly composed of gelatinous zooplankton, while the young mostly are benthic feeders..
In general, the foods of this species are poor in nutrients. Due to this, the animal is forced to consume large amounts of food daily to meet its metabolic needs..
Sunfish have special adaptations for eating jellyfish. Among these, its thick skin stands out, which provides protection against the numerous stingers or nematocysts that jellyfish possess..
So great it has a small mouth and its teeth are fused, forming a kind of beak. With this, you can cut the hardest prey into pieces, before ingesting them. Those that are gelatinous, it absorbs them and then spits them out.
In addition, in the throat it has pharyngeal teeth, which cut the food into smaller pieces before it reaches the stomach.
The sexual maturity of the So great it is reached when it is between 5 and 7 years old. This species is considered the most fertile among all vertebrates, since the female spawns around 300 million eggs.
Although data on mating are scarce, the observed behaviors infer the existence of a courtship. After this stage, the female releases her eggs into the water, which are externally fertilized by the male's sperm..
The spawning grounds are the North Pacific, the South and North Atlantic and in the Indian Ocean. Fertilization occurs between the months of August and September.
Although the female spawns a large number of eggs, these are small and scattered in the water. This makes the chance of survival low.
Once the egg is fertilized, the embryo transforms into a small larva, which has a tail. This structure disappears after hatching. Regarding the development of the egg, it is asynchronous, which suggests that spawning is multiple.
The eggs are about 0.13 centimeters in diameter and the larvae 0.25 centimeters, so the growth of the sunfish is amazing. The growth rate can be between 0.02 and 0.49 kg / day, and can reach 0.82 kg / day. This allows the sunfish to quickly reach the high weight that characterizes it..
So great It has two larval stages, before reaching the adult stage. In the first phase, the larvae have a round shape and spines, which protrude from the body. In addition, they have pectoral fins and a tail fin. During the second stage the spines disappear and the tail is reabsorbed.
The young move in groups, to protect themselves from predators. However, when they grow up, the sunfish becomes lonely.
More than 40 species of parasites can live on the skin of the sunfish, which leads the animal to try to eliminate them from its body. Some of the most frequent species are the Accacoelium contortum, Lunar thalasoma Y Labroides dimidiatus.
In temperate regions, cleaner fish exist, generally located in those areas where drifting algae are found. These are responsible for removing the parasites that live on the skin of the So great. When the sunfish inhabits the tropics, it receives the help of those fish that are in the coral reefs.
In Bali, this species frequently comes to cleaning stations on the reefs, where groups of school banner fish are found (Heniochus diphreutes). These eat the organisms that live on the skin of the sunfish.
When this fish emerges to the surface, it positions itself on its side or projects its dorsal fin above the water, allowing seabirds to feed on the ectoparasites on its skin. In southern California, seagulls often fulfill that role.
So great it has a short spine and lacks a tail fin. Due to these morphological changes that it has suffered evolutionarily, it has a particular way of swimming. Their swimming method is different from that based on trawling, typical of the vast majority of bony fish..
The push necessary to move is caused by the synchronous movement of the anal fin and the dorsal fins. This force is based on elevation and resembles the flight of birds..
This way of swimming could involve adaptations in the nervous system, related to the locomotor system. In this sense, studies of the anatomy of this fish show that its peripheral nervous system presents differences with other fish of the order Tetraodontiformes..
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