Let’s talk about sex. Shark sex, that is.
While “shark in the water around Florida” should not be news, every year it never fails to send people into a panic even though sharks live in the ocean. But these sharks aren’t following food… they’re following their need to mate. Every year without fail nurse sharks (Ginglymostoma cirratum) gather about 70 miles west of Key West off the Dry Tortugas to find some shark to… well, get busy with. Marine scientists Harold “Wes” Pratt and Dr. Nick Whitney join the sharks in the Sunshine State to study the behavior of these sharks as it relates to their mating success.
“This is the only place in the world where you can study shark mating behavior on a reliable basis,” Whitney told CBS news.
Whitney and Pratt have been coming down to the Florida Keys since the early 1990s with colleagues Dr. Jeff Carrier and Theo Pratt. This yearly meet-up has allowed the researchers to conduct novel research into the reproduction and mating behavior of the nurse shark. ”Before we started, almost nothing was known about shark mating behavior. This particular species is a window into that world. White sharks, blue sharks, hammerheads all mate like this,” Pratt said.
Nurse sharks can reach up to 14 ft (4.3 m) in length and have powerful jaws that allow them to crush through the hard exteriors of shellfish and even mouthfuls of coral as they hunt for fish, shrimp, and squid on reefs. They love warm, shallow waters and can be abundantly observed in the western Atlantic and eastern Pacific oceans. Yet, for how widely distributed they are, scientists still know little about the gene flow between these populations. Nurse sharks seem to have a strong site fidelity as seen in this yearly meet-up between the sexes. It isn’t clear where their common name, ‘nurse shark,’ comes from. Some say it comes from the sucking sound they make when they find prey to eat and vacuum it up, which apparently sounds like a nursing baby. Others think it’s from the word nusse which means ‘catshark,’ while others point to the Old English word for a sea-floor shark, hurse.
The majority of what is known about shark courtship and mating behavior comes from the work of these scientists in this one location because it is the only place in the world where these behaviors can be observed on a predictable basis. The mating dance is taxing, with couples often rolling around and kicking up sand. The male shark has to hold the female in place for copulation to happen, biting her pectoral (side) fin to keep her still enough to insert a clasper (the external male reproductive organ) into her. The female will carry the fertilized eggs in egg cases within her ovaries until the pups are done cooking and ready to be born about six months later.
This research being done in the Dry Tortugas is the longest-running shark behavioral study in the world and the region is the only marine protected area in the world designated to protect a shark mating ground. This is because understanding when, where, and how sharks mate helps scientists and stakeholders who manage these species understand what places and times are most important for their survival. This research can also help explain their long-term migrations and habitat use. While most of the past research was focused on direct observations and video analysis of the animals that were taken from the shallows during daylight hours, new technology has allowed the scientists to collect longer, more detailed behavioral records at all hours including during the night and in deeper water where observations were hard or impossible to do.
While nurse shark mating season is May-July, there are still some stragglers who are getting it on. If you see some sharks getting jiggy with it, don’t disturb them (or worse, grab their tails or try to give them a kiss). It’s best we leave them to it, as we all can all understand how distractions during this time are seldom welcome.
