New Zealand Tuataras: How Its Speedy Sperm Could Save the Endangered Species

New Zealand's endemic tuataras are the sole survivors of an ancient reptilian order that was once widespread across the country. Today, only a fraction of the reptile's historic range survives on a small offshore eco-sanctuary.

Despite aggressive conservation efforts to restore the reptile populations, lack of knowledge about their reproduction equates to a majority of conservation techniques taken off the table. However, thanks to new research in New Zealand, tuatara's speedy sperm conservationists may be able to help save the endangered species.

What Are Tuataras?

According to New Zealand's Department of Conservation, tuataras are a rare reptile family found only in the country of New Zealand. These small reptiles are the only remaining survivors of an order of reptiles that once thrived in the age of dinosaurs.

Once found throughout the mainland, the reptiles are now only surviving in the wild on about 32 islands of New Zealand. Some of the major threats to the tuataras are rats, mice, low genetic diversity, habitat destruction, and poaching.

Adult males of the species can reach lengths of 0.5 meters and can weigh about 1.5 kg when fully grown. The colors of the endangered tuataras change throughout their lifetime and can range from olive green to brown to orange-red. The reptile's diet mostly consists of invertebrates, such as millipedes, spiders, worms, weta, and beetles.

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Conserving the Endangered Tuataras

Tuataras, other than their ancient blood, are especially unique among other reptiles due to males not possessing a penis or hemipenes, which create a challenge for conservationists to collect sperm. However, in a research published in the journal PLOS ONE, titled "Initial Collection, Characterization, and Storage of Tuatara (Sphenodon punctatus) Sperm Offers Insight Into Their Unique Reproductive System," researchers described how they managed to collect and characterize the tuatara's live sperm for the first time.

Surprisingly, the team found that the tuatara's sperm are the fastest swimmers of any reptile species studied to date. This could potentially boost conservation efforts unique to New Zealand's treasured species.

One of the first challenges conservationists had to get past was how to sample the reptile's live sperm. The male reproductive anatomy of the species is more bird-like than a reptile. Tuataras, as reported by Phys.Org, transfer sperm when males align their cloaca with the female's. Researchers discovered that the best technique to collect viable sperm samples was just after the 'cloacal kiss,' when the sperm was slightly visible on the female cloaca's edges.

For the first time ever, conservationists were able to collect, image, and measure the speed of viable tuatara sperm. Despite tuatara generally living a long slow life, it caught the team by surprise to know how fast the sperm were swimming.

The team theorizes that the speedy tuatara sperm may be an adaptive reproductive effort of the male. With reptiles normally having intromittent organs, such as hemipenes and penises, to aid in sperm delivery, the tuatara solely relies on the ability of their sperm to quickly swim inside the female's cloaca after mating.