FISHERY BULLETIN: VOL. 73, NO. 2 



E. /meatus 



K. pelamis 



T. albacares 



T. thynnus 



Figure 1. -Transverse sections of four warm-bodiea species showing the position of central and lateral retia mirabilia (r) that function 

 as vascular heat exchangers. The major blood vessels supplying retia are: dorsal aorta (da), posterior cardinal vein (pcv), cutaneous 

 arteries (ca), and veins (cv). Veins are shown with larger diameters and thinner walls. Red muscle distribution (shaded areas) is also 

 depicted. Noted that the position of cutaneous arteries and veins in Euthynnun lineatuit is reversed compared to that in other species 

 and that only an epaxial pair is present. Also, Thunnus thynnus does not have a posterior cardinal vein. Frigate mackerels (Auxis) are 

 not shown but are very similar to Euthynnus. Data contained in this figure are from various sources cited in the text. 



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