New Predator of the Deep

South Carolina Hammerhead (Photo credit to South Carolina University)

            Scientists are buzzing about a new species of hammerhead shark discovered in South Carolina. Joe Quattro, an ichthyologist from the University of South Carolina, takes claim to this amazing discovery. To officially classify it as a new species it required extensive fieldwork, genetic testing, and literature research. This rare species, Sphyrna gilberti, is now called the South Carolina hammerhead. The species is very similar in appearance to the common scalloped hammerhead, so genetic evidence was needed to prove they were two different species. The story Quattro relays about the time and dedication it took to confirm the new shark species is just as impressive as the discovery itself. Quattro accomplished an amazing feat and this addition to the science community will make a lasting impact on marine biology research in the future.

            Quattro has been a biologist at USC since 1995 and has focused his research on fish populations in freshwater rivers that connect to the ocean. His main fields of interest as a scientist are conservation, genetic diversity, and taxonomy. His research focuses on the four South Carolina river basins, the Pee Dee, Santee, Edisto, and Savannah. He spent many hours on the rivers collecting genetic data from mainly pygmy sunfishes and basses.  Then he branched out to study short-nosed sturgeon and shark pups.

            The South Carolina coast is a popular breeding ground for several shark species. Hammerheads, specifically, will birth their young at the boarder of the ocean and estuary. After birth, the shark pups remain local for roughly a year until they grow larger enough to enter the open ocean ecosystem.

            Quattro and his student, William Driggers III, studied and collected genetic data from these hammerheads regularly. Genetic analysis showed that the common scalloped hammerhead, Sphyrna lewini, had two different genetic signatures in both the mitochondrial and nuclear genomes. Quattro and Driggers resorted to old literature to try to answer the genetic differences. They found that Carter Gilberti, a curator at the Florida Museum of Natural History from 1961-1998, described a hammerhead that had 10 fewer vertebrae than the common hammerhead. The hammerhead was found in 1967 near Charleston, S.C. At that time science and technology was not as advanced as it is today, so scientists never determined if it was a different species.

            This discovery is truly an accomplishment for Quattro and Driggers and the scientific community because it furthers our knowledge of the ocean and its species. To honor Gilberti, Quattro and Driggers named the species after him, Sphyrna gilberti, because he unknowingly helped them solve the mystery. Further research needs to be conducted on the South Carolina hammerhead as a population. Quattro wants to learn more about their population numbers and their place in the ocean ecosystem. Finding a new shark species is not only a huge success for Quattro, but it brings awareness to the South Carolina hammerhead as a species.

 

Photo Credit to University of South Carolina

University of South Carolina. "New species of shark: Carolina hammerhead." ScienceDaily, 7 Nov. 2013. Web. 12 Nov. 2013.

www.sciencedaily.com/releases/2013/11/131107170959.htm

Ant Defenders

Stem cavity of the Ecuador laurel tree

Azteca ant detects a caterpillar on a leaf of the Ecuador laurel tree.

            The Ecuador laurel tree, Cordia alliodora, developed an interesting and effective method to protect itself from herbivore predators. During the dry season the tree has two main threats, lack of water and herbivore consumers, so the tree devised a defense strategy to mitigate the lost of leaves to predators. The Ecuador laurel tree created a mutualistic relationship with Azteca pittieri ants that in exchange for living in the tree offer protection against herbivores.

The ants nest in the stem cavities of the tree and feed on the pink scale insects that also live within the tree. The pink scale insects feed on the sap secreted by the tree and produce a sugary substance called honeydew that serve as the ant’s food source.  The ants are small in size compared to other herbivores, but they work in groups to attack predators. For example, they will surround a leaf-eating caterpillar and bite its underside until it falls off the leaf.

This relationship guarantees the tree protection, but it comes at an ecological cost. The pink scale insects consume the tree’s sap, so the tree is constantly using its energy reserves to produce more sap. It is arguable that the tree would seem better off to hoard its sap during the dry season because if the sap supply is depleted, then the tree will die. Furthermore, even if the tree did not perish, a low supply of carbon would be detrimental for the rainy season. This relationship is unusual and requires a delicate balance for survival.

Researchers wanted to investigate this relationship further, so they observed the tree and ant behavior in 26 sites, all with varying precipitation levels. They reported that in the drier areas the tree and ant relationship was stronger than in the wetter regions. It was also observed that in the drier sites there were more pink scale insects, thus supporting a larger ant population. The researchers observed that the ants in the drier regions were much better defenders, with quicker reaction times and defense movements, than in the wetter regions.

It can be gathered that the ants serve as “tree insurance” because the cost of herbivory is high. The cost of sustaining the ants is cheaper than replacing leaves that herbivores eat. The tree would have to replace the leaves each time with energy from the sun. The process of growing a new leaf is not practical, so the tree invests in defense. Although this relationship is peculiar and defies common ecological trends, it has led to the success of the Ecuador laurel tree.

 Photo Credit to Science News

Zielinski, Sarah. In dry times, these trees invest in ants. Science News: Magazine of the Society for Science and the Public. Science News, 7 Nov. 2013. Web. 9 Nov. 2013.

https://www.sciencenews.org/blog/wild-things/dry-times-these-trees-invest-ants

The cavemen might have had company

Picture courtesy of Science News

            Scientists are in awe over the recent discovery of a new translucent snail species that resides in the underground caves of Croatia. The snail, officially named Zospeum tholussum, is a terrestrial snail that occupies wet subterranean areas. The snail is completely translucent with an average shell height of 1.55 millimeters, which is comparable to the thickness of a penny. The unearthing of this extraordinary species is due to the work of Alexand Weigand of Goethe University in Frankfurt, Germany.

            Wiegand found the snail while exploring the Lukina jama-Trojama cave system which has an average air temperature of 3.3°C, a water temperature of 5.1 °C, and a humidity level of 100%. Wiegand captured the only living specimen at 800 meters for further research. Wiegand continued down the cave system and discovered vast quantities of empty shells 800 to 1400 meters down. The inter-workings of the Lukina jama-Trojama cave system and the snail's location are depicted in Figure 1. While Wiegand travelled throughout the cave system he noticed that all the empty shells had a milky white appearance, which could be attributed to aging after the snail deceased. 

            Scientists believe that the new snail species is similar to the common terrestrial snail because of shared characteristics. For example, the Zospeum tholussum demonstrates a sedate lifestyle with limited mobility. The living specimen and array of shells were found in mud by running water, which suggests that they relied on the cave water systems for transportation. The snail and its biological role in the cave system are still under investigation. Further research needs to be conducted to determine their range within the cave system and explain the great quantity of shells Weigand found.

Figure 1.  The Lukina jama-Trojama cave system and snail depths.

Picture courtesy of Science News

Bohac, Allison. "Clearly New Snail." Science News: Magazine of the Society for Science and the Public. Science News, 2 Nov. 2013. Web.  3 Nov. 2013.

https://www.sciencenews.org/article/clearly-new-snail