Hydraulic control of tuna fins: A role for the lymphatic system in vertebrate locomotion

Abstract

Hydraulic fins The lymphatic system in fish has much the same function as it does in mammals—immune response and homeostasis. Pavlov et al. show, however, that in the scromboid (tuna and mackerel) family of fish, this fluid homeostasis function has been co-opted to help facilitate dorsal fin rigidity and movement (see the Perspective by Triantafyllou). In bluefin tuna, a series of lymphatic vessels are integrated with muscles that allow the fish to raise and stiffen their dorsal fin. This provides extra stability during swimming. Science , this issue p. 310 ; see also p. 251