Happy Shark Week!! In this post, we take a look at how fasting may harm young tiger sharks.
Sharks LOVE to eat fish, which are packed with protein and fats. In fact, fat is a major energy source for sharks and high levels of circulating fats are associated with better body conditions in tiger sharks. To handle their diet, sharks need healthy livers and gallbladders to produce and release bile, which helps them (and us) digest fats.
Sharks do not eat every day. Tiger sharks (Galeocerdo cuvier), for example, can go days or even weeks between meals. During these fasting periods, bile acids can build up in their bodies as the liver continues to produce the substance even in the absence of food. Researchers suspected that such accumulation may come with health risks.
Because many shark populations are endangered, a team of researchers wanted to know if bile accumulation might harm young sharks and possibly contribute to population declines. Their research revealed that female tiger sharks with bile buildup developed liver cysts filled with bile, showed signs of liver inflammation, and had high levels of bilirubin, a bile pigment, in their circulation.
Although the animals had fats stored in their liver, which may be released during fasting, the high levels of bilirubin and presence of cysts suggest that the sharks may have had trouble releasing bile resulting in the leakage of the pigment into their blood. Although these findings only examined a small piece of the puzzle, they shed some light on possible reasons for their population declines.
Source:
Wosnick N, Chaves AP, Niella YV, Takatsuka V, Hazin FHV, Nunes JLS, Morick D. Physiological impairment as a result of bile accumulation in an apex predator, the Tiger shark (Galeocerdo cuvier Peron & Lesueur, 1822). Animals. 10(11): 2030, 2020. Doi: 10.3390/ani10112030
Categories: Diet and Exercise, Illnesses and Injuries, Most Popular, Ocean Life, Sharks
Tags: animals, bile, diet, fasting, food, health, nutrition, shark week, wellness
Life Lines by Dr. Dolittle 