Communication and Perception
Like most dolphins, Tucuxis use a variety of whistles and clicks to communicate with conspecifics. Among delphinids, evidence suggests that species' size has a linear effect on whistle pitch, with smaller species having higher pitched whistles and larger species having lower pitched whistles. Tucuxis align with this relationship, and as one of the smallest extant dolphin species, they are known to have some of the highest pitched whistles when compared to other dolphins (e.g., 16% of whistles exceed 24Hz). Whistle frequency tends to ascend rather than descend during a single whistle. Whistling increases while foraging, and is thought to attract conspecifics to where food is abundant; suggesting a co-operative rather than competitive attitude between conspecifics. Like other delphinids, Tucuxis use echolocation to help them find prey.
Tecuxis use their vision to perceive the local environment, and despite living in a freshwater environment, have a number of ocular features that are similar to those of many marine dolphins. Tucuxis have two high density ganglion areas, a feature which is common among delphinids and helps them process visual information more efficiently than Amazon River dolphins, which have only one. Being originally adapted for life in a saline environment, however, may negatively affect their ability to see objects in freshwater at high resolution. Evidence suggests that although their clarity of vision is less than that of true river dolphins, it is better than that of marine dolphins. What they lack in eye sight, however, they make up for in their ability to echolocate prey and potential predators.
Communication Channels: acoustic
Perception Channels: visual ; echolocation
- Azevedo, A., M. Van Sluys. 2005. Whistles of tucuxi dolphins (Sotalia fluviatilis) in Brazil: Comparisons among populations. Acoustical Society of America, 117/3: 1456–1464.
- Mass, A., A. Supin. 1999. Retinal topography and visual acuity in the riverine tucuxi (Sotalia fluviatilis). Marine Mammal Science: 351-365.