Counting on Numbers-Numerical Abilities in Grey Bamboo Sharks and Ocellate River Stingrays

Area of Science:

• Comparative cognition
• Animal behavior
• Elasmobranch biology

Background:

• Research on fish cognition has expanded, focusing on numerical discrimination abilities.
• Few studies have investigated quantity discrimination in elasmobranchs, a group of cartilaginous fishes.

Purpose of the Study:

• To investigate the capacity for numerical quantity discrimination in two elasmobranch species: the grey bamboo shark (Chiloscyllium griseum) and the ocellate river stingray (Potamotrygon motoro).
• To determine if elasmobranchs can solve quantity discrimination tasks using numerical information independently of continuous variables.

Main Methods:

• Animals were trained using two-alternative forced-choice visual experiments.
• Transfer tests were conducted to assess the application of learned knowledge to new tasks.
• Continuous variables were controlled to isolate numerical processing.

Main Results:

• Both the grey bamboo shark and the ocellate river stingray demonstrated the ability to discriminate quantities based on numerical information alone.
• The observed limits and magnitudes of quantity discrimination were comparable to those found in other animal species.
• Significant intraspecific variation and a low success rate suggest quantity discrimination may not be a primary cognitive driver for these species.

Conclusions:

• Elasmobranchs, specifically the tested shark and stingray species, possess the cognitive capacity for numerical quantity discrimination.
• The ecological relevance of quantity discrimination may differ between elasmobranchs and other animal groups previously studied.
• Further research is needed to understand the evolutionary and ecological significance of numerical cognition in cartilaginous fishes.