Molas develop their truncated, bullet-like shape because the
tail fin, which is present at birth, never grows. Instead, it folds into itself as the fish matures, creating a rounded rudder called a clavus.
Mola in
Latin means "millstone" and describes the ocean sunfish's somewhat circular shape. They are a silvery colour and have a rough skin texture. Molas are the heaviest of all the extant
bony fishes: large specimens reach 4.3 m (14 ft) vertically and 3 m (10 ft) horizontally, and can weigh over 2,700 kg (6,000 lbs). Molas inhabit temperate and tropical oceans around the world. Ocean sunfish can become infested with skin parasites, so they often invite small fish or even birds to feed on them. Sunfish sometimes breach the surface up to 3 m (10 ft) in the air in an attempt to shake off parasites. Their food of choice is jellyfish, though they will eat small fish and large amounts of
gelatinous zooplankton and algae as well. Their population is considered vulnerable, as they are frequently snagged in drift gill nets and can suffocate on plastic bags, which resemble jellyfish, their main food source. They breed by producing around 300 million eggs directly into the ocean (
spawning), which are externally fertilized by sperm into the water column. == Taxonomy ==