Endangered sharks, rays further threatened by global food markets

Using DNA barcoding technology, University of Guelph researchers discover a majority of the shark fins and manta gills sold around the world are from endangered species.

Date: August 25, 2017

Source: University of Guelph

Summary:

A majority of shark fins and manta ray gills sold around the globe for traditional medicines come from endangered species, a study has revealed. Using cutting-edge DNA barcoding technology, researchers found 71 per cent of dried fins and gills collected from markets in Canada, China and Sri Lanka came from species listed as at-risk and therefore banned from international trade.

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Hands and Fins Share Common Genetic Origin

by Tanya Lewis, Staff Writer | December 22, 2014 03:27pm ET

Scientists have long wanted to know whether modern hands are related to the fins of fish, and now a new study finally reveals these structures are, indeed, related.

Researchers compared the genetic sequence of an unusual freshwater fish with that of mice, and found that the genesinvolved in the development of the mice's hands and feet are also involved in fin development, which suggests the fins of the fishy ancestors evolved into the limbs of modern land animals.

"Fossils show that the wrist and digits clearly have an aquatic origin," Neil Shubin, an organismal biologist at the University of Chicago, said in a statement. "But fins and limbs have different purposes. They have evolved in different directions since they diverged."

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The Evolution of Fins to Limbs in the Land Invasion Race

July 5, 2013 — Why did animals with limbs win the race to invade land over those with fins? A new study comparing the forces acting on fins of mudskipper fish and on the forelimbs of tiger salamanders can now be used to analyze early fossils that spanned the water-to-land transition in tetrapod evolution, and further understand their capability to move on land.

Research conducted by Sandy Kawano and Richard Blob at Clemson University compared terrestrial locomotion in tiger salamanders and mudskipper fish, which have similar characteristics to early tetrapod ancestors.

The researchers filmed these organisms as they walked over a force platform which measures forces like a bathroom scale but separates them into 3 directions (upward, fore-aft, and side-to-side). They compared the forces experienced by the pectoral fins of the mudskipper fishes to the forelimbs and hind limbs of walking tiger salamanders. The results showed that that mudskippers' pectoral fins experience more medial forces than the limbs of salamanders, and that the forelimbs could have a played a similar weight-bearing role as the hind limbs.

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