Heather Bracken-Grissom, marine sciences professor in the FIU Department of Biological Sciences, has helped answer one of the most debated questions among evolutionary biologists: Did the hermit crab evolve into the king crab, or did the king crab evolve into the hermit crab?
Since the 19th century, science has suggested hermit crabs and king crabs are close relatives, despite their strikingly different appearance. Hermit crabs are small and depend on a shell for protection. King crabs are one of the largest crustaceans and do not have a shell, since they use their external skeleton to defend themselves. Both species belong to the infraorder Anomura – with more than 2,500 species within the infraorder, they are all very diverse in structure and ecological adaptations. As science would have it, hermits evolved into kings.
“The reason why it’s taken so long to solve this mystery is because now we can use modern technologies and techniques that weren’t available before,” Bracken-Grissom said. “DNA sequencing has evolved leaps and bounds in the past few decades and now we can collect data like never before. Also, it’s taken about 30 years of collecting samples to really be able to do a comprehensive study of this group.”
Despite their seemingly different body structures, both crabs have one, key feature in common: an asymmetrical abdomen. The hermit’s abdomen is concealed and coiled inside its shell. The king’s asymmetrical abdomen is found in the adult form.
Read more at: Phys.org