Category: Rays and Bony Fish


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The Mola Mola Ocean Sunfish

Imagine an irregularly shaped disk with exaggerated fins, bulging eyes and a tiny mouth below a bulbous flat head flopping around at the surface of Monterey Bay and you have discovered the ocean sunfish, Mola mola!  As you approach this mystical creature, it suddenly dives out of sight undulating its dorsal and ventral fins as it disappear into the depths. The Mola mola is the heaviest   bony fish known to exist in the ocean realm.   It sustains itself on a diet of gelatinous creatures such as the egg yolk sea jelly among other planktonic jellies found in Monterey Bay. Beginning life as a tiny minuscule drifting egg, an ocean sunfish will begin to grow increasing its size by over 50 million times until it reaches the size of a minivan. To put this into perspective, imagine a fully-grown marine toad, Bufo marinus weighing over 120,000 pounds that began its journey though life as a tiny tadpole, weighing less than a gram. Mola mola are acknowledged in the Guinness Book of World Records as producing the largest number of eggs of any fish ever recorded. A single female ocean sunfish held 300 million eggs. The ocean sunfish thrives in temperate and tropical oceans including the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, and the Mediterranean Sea and on rare occasions, the Bering Sea. While their preferred habitat is open ocean, they may sometimes wander into kelp forests and deep coral reefs.

Natural History Notes

Its is intriguing to note that adult ocean sunfish lack a swim bladder, the organ in fishes that gives them the ability to control their buoyancy.  Ichthyologist once assumed that ocean sunfish traveled at the whim of prevailing currents drifting along with other planktonic forms of life. However, studies have revealed that the Mola mola can reach speeds of over 3 kilometers per hour and cover over 25 kilometers per day. While often appearing lethargic and slow moving near the surface, they are quite capable of speed and swimming to depth.aaScreen Shot 2017-07-01 at 8.42.11 PM

 

However, since ocean sunfish are often drifting at a pelagic snail’s pace, they are subject to a high degree of parasitism. Seeking slow moving creatures such as sea turtles basking in the sun, whales in breeding lagoons and meandering ocean sunfishes, a variety of parasites will climb aboard for an easily obtained and predictable meal.

 

Another interesting story can be woven between Mola mola and Bufo marinus, the lethargic marine toads of Tropical America. Oozing from the paratoid glands of these impressively large toads is a milky substance which contains bufotoxin, a strong neurotoxin. The ocean sunfish is classified among the Tetraodontiformes, an order of marine fish which contain a powerful neurotoxin, tetrodotoxin. Unlike their cousin the pufferfish, ocean sunfish probably lack the deadly toxin.  However, the toxins derived from both the marine toad and the Mola’s cousin, a Caribbean pufferfish have been used in the Haitian traditional practice of zombism.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Considered a pelagic wanderer, The Atlantic Devil Ray, Mobula hypostoma searches for its preferred  prey, crustaceans such as shrimp and krill. Employing  its  cephalic fins to focus  food towards  its mouth, it sometimes feeds in shoals along the Florida Gulf Coast.

Each year, Blue Water Ventures travels to the Sea of Cortez on a 10 day expedition where we sometimes have the extraordinary experience of snorkeling with Mobulas as shown in the video.

OLYMPUS DIGITAL CAMERALacking a defensive spine, Mobulas find protection through sheer speed and in the company of other rays. Their common name “devil ray” is derived from the curled appearance of their cephalic fins when not in the feeding mode.