Sunfish
Mola mola
IUCN Status:Vulnerable
The ocean sunfish, or mola mola, is a regular visitor to our summer coastlines. This odd fish often greets boaters, paddleboarders and kayakers in inshore waters during summer months.
What do they look like?
This huge flat-sided fish has a heavily reduced tail and overly extended dorsal and ventral fins. At the front end you have a mouth like a vacuum cleaner, evolved to suck up squid, small fish, jellyfish, salps and other deep-sea softies in mere seconds. It’s so effective that the sunfish ranks as the heaviest bony fish in the ocean, with a large specimen weighing more than two tons and measuring four metres from fin to fin.
Sunfish have a much-reduced layer of scales, to the point where they are just tiny, hardened pimples embedded in a thick flesh. This leaves the sunfish without an armoured shell, making it an easy target for parasites which can burrow through the skin and feed on the juices within.
Where can they be found?
They're primarily found in southern and western parts of the UK in the summer months, but can be found across UK waters.
Did you know... The mola mola is one of the heaviest bony fish on Earth. It is second only to its giant cousin, the Southern sunfish (Mola alexandrini), which currently holds the record. Even in second place, a mola mola can weigh an incredible 2,000lb! While their basking behaviour earnt them their 'sunfish' name, the scientific mola mola name stems from the Latin word for millstone, because they look like huge grey stone discs.
Key facts
Sunfish are found in temperate to tropical oceans in both hemispheres, and while they are known for diving and hunting in deep, dark waters, they are dedicated heliophiles, or ‘sun-lovers’. In fact, the common name of sunfish doesn’t just come from its circular chunky figure but also its habit of lying in the warm surface waters working on its tan.
By basking at the surface, exposing its pale circular side to the sun, the sunfish signals that an all-you-can-eat parasite buffet is open for passing seabirds. These feathered friends can then descend on the sunfish and, with sharp beaks and keen eyes, winkle out even the most stubborn of blood-sucking hitchhikers.
| IUCN status | Vulnerable |
|---|---|
| Length | Sunfish have an average length of around 1.8m, but have been known to grow to over 3m long. Their bodies are also incredibly wide, measuring an average 2.4m between their top and bottom fins. |
| Weight | One of the heaviest bony fish in the ocean, the mola mola weighs roughly 2,000lb. |
| Speed and distance | They travel at a leisurely 2mph and can cover roughly 16 miles per day. |
| Diet | They mostly eat smaller fish, squid and prawns. Being slow movers, they hunt through floating weeds and often dive 200m below surface level to reach their prey. |
