Collaborators: F. James Rohlf (Stony Brook) & Michael G. Frisk (Stony Brook)

Enlarged pectoral fins are a major feature of body plan evolution in batoid fishes (i.e., skates, rays, and their relatives), and provide the primary means of propulsion for most species (Fig. 1). Consequently, variation in pectoral fin shape is closely related to patterns of habitat utilization. This research aimed to understand patterns of morphological diversity and evolution of batoid pectoral fins, challenging the widely believed notion that skates comprise a morphologically conserved clade.

shark outline (defense)
Figure 1. Major pectoral fin morphotypes in batoids.

This work revealed that over half of pectoral shape variance in batoids could be attributed to variation in aspect ratio (Fig. 2), a functionally significant property of fin shape, and that there was a strong and significant relationship between fin morphology and swimming mode (Fig. 3). Furthermore, I found that despite their reputation, skates were among the most morphologically diverse batoids and that a re-evaluation of their functional breadth was warranted. This research provides valuable context for the evolutionary history of the most species-rich group of extant cartilaginous fishes, including insights on the transition from benthic to pelagic forms.

Figure 2. PCs 1 and 2 of batoid pectoral shape variation.


Figure 3. Aspect ratio and PC 1 of batoid pectoral shapes plotted against wave number (a proxy for swimming mode).


Relevant Publications:

Martinez CM, Rohlf FJ & Frisk MG. 2016. Re-evaluation of the morphological diversity of batoid pectoral fins: consequences for locomotion and lifestyle. Journal of Morphology. 277(4), 482-493.


Funding Sources:

Turner Summer Research Grant (Center for Inclusive Education, SBU)

Lerner-Gray Fund for Marine Research (AMNH)