Anatomy of the mechanosensory lateral line canal system and electrosensory ampullae of Lorenzini in two species of sawshark (fam. Pristiophoridae).

It has long been assumed that the elongated rostra (the saws) of sawsharks (family: Pristiophoridae) and sawfish (family: Pristidae) serve a similar function. Recent behavioural and anatomical studies have shed light on the dual function of the pristid rostrum in mechanosensory and electrosensory prey detection and prey manipulation. Here, the authors examine the distributions of the mechanosensory lateral line canals and electrosensory ampullae of Lorenzini in the southern sawshark, Pristiophorus nudipinnis and the longnose sawshark, Pristiophorus cirratus.

Genetic and historical evidence of common sawsharks Pristiophorus cirratus in the waters of southern Queensland.

In 2011, a male pristiophorid was caught by a prawn trawler north east of Cape Moreton, Queensland, Australia. Molecular analyses confirmed the specimen to be the common sawshark Pristiophorus cirratus. Historical catch data indicate the occurrence of the species in the region but this is the first verified record of P.

Electroreceptive and mechanoreceptive anatomical specialisations in the epaulette shark (Hemiscyllium ocellatum).

The arrangement of the electroreceptive ampullary system and closely related mechanoreceptive lateral line canal system was investigated in the epaulette shark, Hemiscyllium ocellatum. The lateral line canals form an elaborate network across the head and are continuously punctuated by pores. Ampullary pores are distributed in eleven distinct pore fields, and associated ampullary bulbs are aggregated in five independent ampullary clusters on either side of the head.

Electroreception in elasmobranchs: sawfish as a case study.

The ampullae of Lorenzini are the electroreceptors of elasmobranchs. Ampullary pores located in the elasmobranch skin are each connected to a gel-filled canal that ends in an ampullary bulb, in which the sensory epithelium is located. Each ampulla functions as an independent receptor that measures the potential difference between the ampullary pore opening and the body interior.

Electric field detection in sawfish and shovelnose rays.

In the aquatic environment, living organisms emit weak dipole electric fields, which spread in the surrounding water. Elasmobranchs detect these dipole electric fields with their highly sensitive electroreceptors, the ampullae of Lorenzini. Freshwater sawfish, Pristis microdon, and two species of shovelnose rays, Glaucostegus typus and Aptychotrema rostrata were tested for their reactions towards weak artificial electric dipole fields.