Rajiformes – Skates & rays
The flattened version of sharks
A closely related group to sharks that shares a striking resemblance in terms of their skeletal structures, fins, and gill slits. However, they possess distinctive features that set them apart and make them fascinating marine creatures. One of the key differences is the placement of their gill slits, which are located on the ventral side of their flat bodies, unlike sharks.
One of the most remarkable characteristics of Rajiformes is their large pectoral fins, which form a disk-like shape and are attached to the sides of their heads. These unique fins enable them to perform ‘Rajiform locomotion,’ a specialized mode of movement that sets them apart from other marine life. Additionally, they have the ability to punt along the ocean floor, showcasing their adaptability in diverse aquatic environments.
Many species within the Rajiformes order are adorned with thorn-like dermal denticles covering their skin, giving them an intriguing and peculiar appearance. Some of these species, especially those that dwell on the ocean floor, utilize specialized spiracles on their heads. These spiracles allow them to draw in water, facilitating respiration without ingesting mud or debris. The ingested water is then directed over their gills, ensuring effective oxygen exchange.
Unlike sharks, Rajiformes exhibit a dental adaptation characterized by rounded, cobblestone-like teeth arranged in rows. These teeth are specialized for crushing the shells of mollusks and crustaceans, highlighting their unique feeding strategies. Another distinct anatomical feature is their fixed upper eyelid, which differs from the freely moving nictitating membrane found in sharks.