Remember Taz? That lovable, mischief-making cartoon tasmanian devil who traveled around in a mini-tornado of dust? What you probably don’t remember from those cartoons is Taz biting the faces of other devils, aiding the spread of a contagious form of cancer.
Tasmanian devils are rapidly face-cancering themselves to extinction. If we don’t do something soon, those weird little down-under devils will be gone forever.
Enter: electroejaculation. Yes, it is exactly what it sounds like. An electric probe is inserted into the rectum of an anesthetized male animal (or human; this is also used for some infertility treatments). The probe stimulates the prostate and induces the animal to, um, provide a sample.
A paper published this August in the journal Reproduction, Fertility, and Development, presented an evaluation of this technique for use on male tasmanian devils. The hope is that by collecting and saving devil sperm, it can be used in the future for artificial insemination. And given the risk of contracting face cancer during sex, artificial insemination might be the way to go for devil ladies.
According to the paper by T. Keeley and colleagues in Australia, electroejaculation (EEJ) has been attempted with tasmanian devils in the past, but with disappointing results. Either there was only an erection, with no semen collected, or the semen contained very little sperm. It was thought that maybe semen from tasmanian devils and their close relatives wasn’t able to be collected using EEJ. And Keeley et al took this as a challenge.
Let’s take a moment to step back and admire the dedication of the brave scientists out there who collect semen from endangered animals. EEJ is not the only method, though it is widely used. In addition to EEJ, some researchers perform manual stimulation on animals such as elephants and rhinos. Yes people, these are jobs that no one wants to do.
Anyway, back to Taz. The devils used in this study had facial tumors and had been collected for euthanasia. Before being put down, the researchers tested their different EEJ protocols on each devil. There is an extremely detailed description of the procedure in the paper, which I won’t repeat here. I’ll just say that it involves large amounts of lubricant and emptying of bladders and bowels. There is also a photo.
Within 2 minutes of collection, the samples were analyzed for quality. The presence, amount, and friskiness of the sperm as well as total amount of semen were all measured. After the males were finished (providing the samples), the researchers euthanized and then dissected them to check that everything was A-OK with the plumbing.
19 out of 35 males tested in this study had sperm in their EEJ-collected semen samples. By analyzing all the semen samples, the researchers were able to find the best combination of EEJ techniques to collect samples with the highest concentration of sperm. Unfortunately, none of the devils provided great samples. The best sample was 0.4mL and had only around 300,000 sperm. So, in one sense this was a huge success, because no sperm had ever been obtained from devils by EEJ before (and Keeley et al were able to prove that EEJ could kinda work). On the other hand, there’s still a lot of room for improvement. The information from this study on the male reproductive system could be used to develop other techniques for sperm collection in this species.
In a separate study published at the same time, these researchers also determined that even though devils only mate during a specific season, the males actually make the same amount of sperm regardless of season. That means that researchers could collect semen from this species year-round (yay!). They also found that having face cancer doesn’t affect the male’s sperm production–so they can continue to collect sperm from males who are doomed to die from the tumors.
By the way, you may be wondering how in the hell cancer can be contagious. Don’t worry; it’s normally not. You won’t catch cancer from hanging out with cancer patients. But because the tasmanian devil population is so small, and recently went through what’s known as a bottleneck, almost all tasmanian devils are extremely close relatives of each other. As a result, there is very little diversity in the immunity genes of the tasmanian devils. Cancer cells are spread to a new individual by biting and scratching. Because of the low immune gene diversity, the immune genes in the recipient are identical to the immune genes in the cancer cells. As a consequence, the host doesn’t recognize the cancer cells as foreign, so the immune system never attacks.
Unfortunately, tasmanian devils really like to bite each other, especially on the face, so there doesn’t seem to be any end in sight to the spread of this disease. It’s also not the disease itself that usually ends up killing the animal. Instead, because the tumors interfere with feeding, the devils generally starve to death. (For a recent story about this disease, check out this article).
The disease may even be changing the devils’ breeding behavior. Tasmanian devil females used to start breeding around the age of 2, but perhaps because many of them no longer live that long due to the disease, they have started breeding much earlier, around the age of 1.
Hopefully, with the help of this recent research, our brave scientists can soon figure out a more efficient way to collect devil sperm to preserve this species far into the future. Because do we really want to live in a world without Taz?
- Keeley T, Harris M, McGreevy PD, Hudson D, & O’Brien JK (2012). Development and evaluation of electroejaculation techniques in the Tasmanian devil (Sarcophilus harrisii). Reproduction, fertility, and development, 24 (7), 1008-18 PMID: 22935162
- Keeley T, McGreevy PD, & O’Brien JK (2012). The effects of season and devil facial tumour disease on the reproductive physiology of the male Tasmanian devil (Sarcophilus harrisii). Reproduction, fertility, and development, 24 (7), 999-1007 PMID: 22935161