“Okay. All my life, I had a lump at the back of my neck, right here. Always, a lump. Then I started menopause and the lump got bigger from the “hormonees.” It started to grow. So I go to the doctor, and he did the bio… the b… the… the bios… the… b… the “ba-bopsy.” Inside the lump he found teeth and a spinal column. Yes. Inside the lump… was my twin.” – Aunt Voula, My Big Fat Greek Wedding
Andrea Martin is a genius, a straight-up acting genius. She was genius on Sesame Street and on Broadway and of course in this movie, and as a result since 2002 I’ve been:
- Terrified of any sort of bodily lump
- Sympathetic to the plight of vegetarians trying to explain themselves
- Aware of the concept of biopsy.
A biopsy is an investigative surgery; it doesn’t kill the subject, but provides information to the doctor or researcher performing the operation. In Aunt Voula’s case, it provided some really unexpected news, and Team Sousa hopes for revelations of the same magnitude (if not the same comedic heights).
That’s right, in addition to our observational data, we’ve started collecting genetic information via dolphin biopsies. Using a special rifle and large, red, sterile, buoyant darts, we (really just Tim, but it’s a team effort) take careful aim at a peduncle (dolphin back, below the fin) and fire, hoping to remove a neat plug of skin and blubber. This sample gets preserved on ice, shipped back to Adelaide, and analyzed to determine the sampled dolphin’s sex and potential genetic relationships.
*This photo shows the whole red dart en route to contact with a Sousa peduncle. The actual sample taken is much smaller (5mm in diameter) and likely couldn’t be seen from this distance.
It does feel like a drastic procedure- I mean, we do actually shoot at the dolphins with a rifle. But the dolphins barely react, generally diving on hearing the noise of the dart hitting skin or water, and then returning to whatever it was they were doing before. (According to Krützen et al., 2002, dolphins react the same way whether they were hit or missed, indicating that it’s really the sound and disturbance of the dart that causes them to duck.) Additionally, the scar created by the biopsy rifle has been observed in several dolphin populations (this method is well-documented and historically proven among people who study cetaceans) to disappear within a month or two. Compared to the gouges and scrapes we see and recognize on Sousa sahulensis and Tursiops aduncus fins, the plug is hardly noticeable.
I don’t advocate shooting anything at dolphins or really bothering them at all (how would you like it?) but short of waiting around for all of our catalogued individuals to turn upside down and wave their genitals through the air, there’s no other way to determine the sex of the various members of our study’s social groups. And the other data (relatedness, genetic distance, etc.) that we will gain will be a fascinating addition to our observations of the fission-fusion groups of mixing dolphins. Do related dolphins spend more time together? How long does a subadult or young adult stay near its mother? Are allied males related to one another?
Most of the time the biopsy rifle stays in its box at the back of the boat. But we’re hoping to collect as many samples as possible to unlock the genetic gold mine that could be present and underlying our Sousa sahulensis’ behavior and environmental needs.
Krützen, M., Barré, L.M., Möller, L.M., Heithaus, M.R., Simms, C., Sherwin, W.B., 2002. A biopsy system for small cetaceans: darting success and wound healing in Tursiops spp. Marine Mammal Science 18, 863–878.
Hi Vicky, Do you know if dolphins have structural differences between the male and female chromosomes like the difference between human X and Y, or is there another place you look?
According to this paper: http://www.ncbi.nlm.nih.gov/pubmed/23661087 (Derivation and characterization of cell cultures from the skin of the Indo-Pacific humpback dolphin Sousa chinensis.) Sousa have 22 pairs of regular chromosomes (compare to humans’ 23) and one pair of sex chromosomes, which do appear to be X and Y like those in humans. So, 44 total chromosomes, and if they’re all the same shape in a karyotype, which is basically a picture of chromosomes, then the dolphin is female. If one of them is a different shape (truncated, probably) then the dolphin is a male. Thanks for the question!