Anatomical Features

 

Cephalic Fins

Cephalic or head fins are flexible appendages located on the head of the manta ray on either side of the large, wide mouth. Typically when manta rays are swimming, these fins are furled or rolled up and mouth is closed.  This makes the animal more streamlined.

 

The furled cephalic fins resemble horns, but are not. Manta rays unfurl these fins when feeding and it appears these fins help to funnel food and water into the cavernous mouth of the manta.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mouth

The mouth of the manta ray is located on the front edge or anterior side of the animal.  It's a very wide mouth and leads to a large cavernous area inside the manta when opened.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Toothband

Manta rays have very small teeth located in a band along the lower jaw only.  This tooth-band resembles a strip of sandpaper.

 

Branchial Filters

In the back of the cavernous mouth, five pair of meshwork gill filters are located.  These 'gill rakers' are commercially valuable in Asia and have led to large scale manta fisheries in some parts of the world.

 

Gills

Manta rays are cartiliginous fish and like all fish possess gills.  Manta rays swallow copious amounts of water through their mouths that passes through cavernous mouth and out their five sets of gills. Respiration occurs in the gills.

 

Head

In rays, the head is fused to the englarged pectoral fins.  In research conducted by Dr. Csilla Ari (2011) the brains of thirteen Mobula japanica, two Mobula thrustoni, and one Manta birostris were compared.  The methodology used was called encephalization quotient (EQ) and expresses a ratio of actual brain size to expected brain size for an animal of a given mass. The results of the study suggest that Manta birostris has highest brain weight among all fish.

 

Eye

A large eye is located on each side of the manta's head. 

 

Spiracle

A slit behind each eye of the manta ray marks the spiracle.  In bottom dwelling rays, water enters through the spiracles and passes out the gills.  Spiracles in manta rays may not be of much use due to water entering the mouth.

 

Pectoral fins

The side or pectoral fins on manta rays have evolved into large triangular wings.  Manta rays use their pectoral fins to propel themselves through the water.

 

Dorsal fin

Manta rays possess a small dorsal fin at the base of their tail. 

 

Pelvic fins

Two pelvic fins are located on the back edge of the manta rays body.

 

Cloaca

Males and females also have a cloaca - a cavity where intestinal, urinal, and reproductive (female) canals come together.  The cloaca is a slit that starts at the upper junction where the pelvic fins meet and runs vertically toward the belly for a few inches.  Below is an example of manta ray waste coming out of the cloaca.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Claspers

Males are distinguished from females by the presence of two claspers (male sex organs) located adjacent to the inside edge of each pelvic fin.  Males also possess clasper glands that are located at the base of each clasper.  Young male manta rays have very small claspers and may be misidentified.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Resources

Ari, C. (2011). Encephalization and brain organization of mobulid rays (Myliobatiformes, Elasmobranchii) with ecological perspectives. The Open Anatomy Journal 3, 1-13.

 

Crow, G. & Crites, J. (2002). Sharks and Rays of Hawaii. Honolulu, HI: Mutual Publishing.

 

Hamlett, W.C. (1999). Sharks, Skates, and Rays: The Biology of Elasmobranch Fishes. Baltimore, Maryland: The John Hopkins University Press.