Eastern shovelnose ray

[4] Recent studies suggest the species may have trichromatic colour vision due to the discovery of three spectrally distinct cone visual pigments in the retinae.

[6][4] The eastern shovelnose ray has a distinct annual and seasonal reproductive cycle with the species mating in winter and giving birth to pups in the summer months.

[8] Although related to sharks, Guitarfish differ significantly in appearance as they have a flat, ray-like disk formed by the joining of the head and pectoral fins.

[6] The teeth of the eastern shovelnose ray are not fused to the jaw but instead are attached to a fibrous connective tissue sheet, a characteristic common to elasmobranchs.

Recent studies using microspectrophotometry suggest that the eastern shovelnose ray may have trichromatic colour vision due to the discovery of three spectrally distinct cone visual pigments in the retinae.

[5] The eyes of elasmobranchs were previously understood to be best suited for dim light, however, the great amount of cone photoreceptors and the presence of a highly mobile pupil suggests that the eastern shovelnose ray is well-adapted to bright environments.

[7] Broken down into more detail, the eastern shovelnose ray's diet includes carid shrimps, penaeid prawns, stomatopods and crabs.

[12] Shovelnose rays are suction-crushing feeders; the broad mouth and prominent jaw in combination with the suction mechanism enables large prey to be caught and consumed.

[12] The particular teeth shape and structure is significant as it enables the species to crush and grind their prey, which is crucial given their diet consists of hard-bodied organisms.

[6] Given their elongated body and extended pectoral fins it is speculated that the eastern shovelnose ray does not feed at great depths but more likely forages in shallow waters.

[12] Studies suggest that the eastern shovelnose ray has an important role in the trophic structure of Moreton Bay given its relative abundance and diet of benthic fauna.

[4] However, studies undertaken in New South Wales and Queensland reveal slight differences in reproductive cycles, which is likely the result of variance in water temperature between the two locations.

[8] Generally, the species mates in winter (July/August), ovulates in November and gives birth in March after an average four-month gestation period during summer.

[13] Unlike other rhinobatidae species found in the Northern Hemisphere, summer is not a period of high reproductive activity for the eastern shovelnose ray.

[8] The eastern shovelnose ray is thought to be yolk sac viviparous, meaning that embryos develop within an egg in the uterus, however this has not been empirically tested.

[8] Elasmobranchs have developed a variety of reproductive adaptations in the uterus to provide young with nutrients, eliminate wastes, and maintain respiration.

[8] Commercial trawling in New South Wales and Queensland report high catch rates of the eastern shovelnose ray, however, the limited knowledge of the reproductive biology of the species means its vulnerability cannot be accurately assessed.

[13] There is a high seasonal variation with double the amount of rhinobatidae landed in winter than in summer; this is likely linked to the migration patterns of the species as they move to shallower waters to give birth.

Eastern shovelnose ray ( Aptychotrema rostrata) photographed at Murrays Beach, New South Wales
Distribution of the eastern shovelnose ray from southern Queensland to southern New South Wales.
Satellite image of Moreton Bay, an area of high abundance of the eastern shovelnose ray in Queensland.