Sawfish are unique marine animals with a distinctive, elongated, flattened snout, called a rostrum, lined with sharp, tooth-like structures. Despite their shark-like appearance, they are rays, identified by gill slits on their underside. All five sawfish species globally face severe threats, classified as endangered or critically endangered by the International Union for Conservation of Nature (IUCN). Their survival is challenged by habitat loss and incidental capture in fishing gear, highlighting the importance of understanding their feeding habits.
Primary Food Sources
Sawfish primarily consume small to medium-sized fish and various invertebrates. Their diet often includes schooling fish like mullet and herring, common in coastal and estuarine habitats. They also feed on bottom-dwelling crustaceans such as crabs and shrimp, and mollusks. Research indicates fish constitute a substantial portion of their diet; molecular evidence from smalltooth sawfish shows fish DNA in up to 71% of their fecal samples. This diverse diet reflects prey availability in the shallow, often murky, waters where sawfish reside.
Hunting Techniques
The sawfish’s rostrum is a sophisticated hunting tool. Its saw-like snout contains thousands of tiny sensory organs, ampullae of Lorenzini, which detect faint electrical fields from living organisms. This allows sawfish to locate hidden or camouflaged prey even in low visibility. Once prey is detected, the sawfish uses its rostrum in several ways. They wave it above the substrate to stir up sediment, uncovering buried invertebrates. They can also slash the rostrum through schools of fish, stunning or injuring multiple prey. The saw can also pin prey against the seafloor for easier capture.
Dietary Adaptations
Sawfish diets can change based on their size, age, and the specific environment they inhabit. Juvenile sawfish forage in shallow, protected nursery areas like mangrove forests and estuaries, consuming smaller fish and benthic invertebrates such as crustaceans and mollusks. As they mature and grow, sawfish move into deeper coastal marine waters, and their diet expands to include larger fish species. Some species, like the largetooth sawfish, are euryhaline, meaning they can tolerate a wide range of salinities and are found in freshwater river systems, estuaries, and coastal marine environments. This adaptability allows them to exploit different prey resources available across these varied habitats, reflecting the local availability of food.