The megamouth shark is a rare shark and a large species, reaching weights of 2700 pounds (1215 kg). However, it is the smallest of the three species of filter-feeding sharks, behind the whale shark and the basking shark. The megamouth shark gets its name from the remarkably large, circular mouth. On an individual approximately 16 feet in length (5 m), the mouth is approximately four feet across (1.3 m). This species has only been observed in the wild a few times, and less than 60 individuals are known by scientists to ever be captured or observed.
Megamouth sharks live from near the surface to as deep as 15,000 feet (4600 m). Like many species with a deep-sea affinity, scientists believe megamouth sharks only come near the surface at night and spend most of their lives in the dark. They are filter feeders and swim with their mouths constantly wide open in order to filter out their preferred planktonic prey. The inside of their mouths are covered with light producing organs that may be used to attract pelagic crustaceans and other potential prey.
Though it is one of the largest sharks in the world, the megamouth shark was only discovered by scientists in 1976. Even large species may go undiscovered in the large deep sea. As commercial fisheries keep pushing to deeper depths to target new species to market as food, new discoveries are constantly being made. The first known megamouth shark was accidentally captured when it became entangled in a sea anchor attached to deep naval equipment near Hawaii. Since that time, only a relatively few dozen individuals have been captured, including a very small number of juveniles. With increasing deep-sea fishing operations, the time between captured individuals has recently become shorter.
Megamouth sharks mate via internal fertilization and give live birth to a small number of relatively large young. Though they give live birth, these sharks do not connect to their young through a placenta. Instead, during the gestation period, the mother likely provides her young with unfertilized eggs that they actively eat for nourishment. After they are born, young megamouth sharks immediately become filter feeders. The megamouth shark is not targeted by commercial fishers, but it is often sold when captured accidentally in fisheries targeting other species. It is likely naturally very rare, but scientists do not believe that they have sufficient knowledge of this species to determine its conservation status.
Oceana joined forces with Sailors for the Sea, an ocean conservation organization dedicated to educating and engaging the world’s boating community. Sailors for the Sea developed the KELP (Kids Environmental Lesson Plans) program to create the next generation of ocean stewards. Click here or below to download hands-on marine science activities for kids.