Shark Chronicles 032 - New beginnings

After many heartfelt goodbyes and promises of reunions from the departing September interns , the remaining three interns (Victoria, Beverly and Simone) welcomed the next batch of interns to the SAMPLA family Wednesday afternoon. They definitely have some big shoes to fill! However, if first impressions are any measure of character, we’re sure that each of the new interns will bring the same level of enthusiasm and work ethic to the SAMPLA team.

The new interns certainly started their first week with a bang! Not only were both the Thursday and Friday chum trips lucky enough to spot not one, but two 5 meter sharks (a rarity in Mossel Bay), they all got a little taste of celebrity.

A journalist from BBC World News recently approached SAMPLA to do a piece on the unique interaction between white sharks and people (or rather lack thereof) despite their relative proximity to each other here in Mossel Bay. The journalist observed two chumming trips to get some general footage of what we do on the boat as white shark researchers, as well as catch the bite meter in action, recording the bite strength of the shark. He took several action shots of the interns performing their respective duties, much to the delight of those lucky enough to score some possible air time in the upcoming program. With regards to the bite meter scene, SAMPLA director Enrico Gennari and his team were rewarded with some success. Unfortunately this was only an investigatory bite, no stronger than that of the average human compared to the impressive bite force that white sharks are capable of. This really goes to show that white sharks are conscious predators, only seldom “going for the kill”.

The SAMPLA team is now eagerly awaiting their silver screen debut on BBC next week!

Simone Lewis-Koskinen (SAMPLA intern)

Shark Chronicles 004 - Megalodon: the Prehistoric Predator

The Megalodon, Meg, (Carcharodon megalodon), is a prehistoric shark, amongst the largest and most formidable of the extinct marine predators. This fearsome fish first roamed the world’s oceans 16 million years ago in tandem with a proliferation of marine mammals, species of primitive whale forms and dolphins on which the Megalodon might have preyed. The Megalodon may have fulfilled an ambitious and unique ecological niche but, ultimately, did not withstand the test of evolutionary time. Most research suggests that the Megalodon’s extinction, about 1.5 million years ago, was linked to the extinction of its prey, a group of slow swimming, baleen whales called Catotheriids. However, the Megalodon’s legacy persists in the form of its smaller but none the less charismatic cousin, the great white shark (“Great White”).

Recently, SAMPLA hosted Creative Difference, the film company producing National Geographic’s PREHISTORIC PREDATORS series. They required the expertise of SAMPLA to assess the biology and behaviour of the Megalodon in context of the Great White. Do our studies of the Great White give us insight into the life of the Megaladon over and above what we know of the Megalodon from the fossil record? In attempt to answer a minuscule aspect of this question, SAMPLA turned to research it had done on the Great White using the bite force meter, a device that measures the voluntary bite power of an animal. All we have from Megalodon is fossilized teeth, which limits the investigation somewhat!

The Megaladon’s teeth show remarkable similarities to adult Great Whites. Both have large and triangular teeth and, more importantly, both are serrated. These serrations serve to remove chunks of a captured prey by sawing. Serrations are a useful adaptation if you capture large prey, marine mammals for example, that can not be ingested whole. Thus as the Great White saws chunks of blubber from a seal, so it is likely the Megalodon sawed blubber from its prey too (the serrated teeth adaptation suggesting that not all its prey could be ingested whole). A Megalodon is estimated to grow to 60ft (18 m) compared to a 20 ft (6 m) for a Great White. Therefore, if one ‘scaled up’ for length, Megalodon potentially had a bite force of nine times that of a Great White. If you have been privileged enough to see the impact of a Great White’s initial ‘crippling’ bite on a seal and its subsequent worrying of the carcass, to imagine that in the context of a Megalodon and its prey is awe inspiring.

However, all this is conjecture – long on speculation and short on information. To compare two great marine predators with such little information is nothing more than indulgence, but thrilling indulgence! All we have is a set of Meg’s remarkable teeth from the fossil strata, and the bones of other animals (potential prey) that occurred concurrently.

RYAN & TOBY