how does a saw fish use its saw
Sawfish The most distinctive feature of sawfish is their saw-like rostrum with a row of whitish teeth (rostal teeth) on either side of it. The rostrum is an extension of the chondrocranium ("skull"),[27] made of cartilage and covered in skin.[33] The rostrum length is typically about one-quarter to one-third of the total length of the fish,[5] but it varies depending on species, and sometimes with age and sex.[1] The rostal teeth are not teeth in the traditional sense, but heavily modified dermal denticles.[34] The rostal teeth grow in size throughout the life of the sawfish and a tooth is not replaced if it is lost.[34][35] In Pristis sawfish the teeth are found along the entire length of the rostrum, but in adult Anoxypristis there are no teeth on the basal one-quarter of the rostrum (about one-sixth in juvenile Anoxypristis).[36][37] The number of teeth varies depending on the species and can range from 14 to 37 on each side of the rostrum.[2][38][note 1] It is common for a sawfish to have slightly different tooth counts on each side of its rostrum (difference typically do not surpass three).[39][40] In some species, females on average have fewer teeth than males.[1][39] Each tooth is peg-like in Pristis sawfish, and flattened and broadly triangular in Anoxypristis.[2] A combination of features, including fins and rostrum, are typically used to separate the species,[2][38] but it is possible to do it by the rostrum alone.[41]
Asian carp Silver carp have become notorious for being easily frightened by boats and personal watercraft, which cause them to leap high into the air. The fish can jump up to 2.5–3.0 m (8–10 ft) into the air, and numerous boaters have been severely injured by collisions with the fish.[3] According to the EPA, "reported injuries include cuts from fins, black eyes, broken bones, back injuries, and concussions.".[4] Silver carp can grow to 45 kg (100 lb) in mass.[5] This behavior has sometimes also been attributed to the very similar bighead carp, but this is uncommon. Bighead carp do not normally jump when frightened.[1] Catching jumping carp in nets has become part of the Redneck Fishing Tournament, in Bath, Illinois.[6] Other parties, such as the Peoria Carp Hunters, have taken advantage of the jumping ability as a mechanism of hunting the carp, in some cases to purge the invasive species.[7]