Crocodile Prof finds adventure in discovery

A lifetime passion for zoology, which started with single-celled pond organisms and progressed up the evolutionary tree to mammals – including camels – shifted into a different gear last September, when University of Queensland’s Professor Gordon Grigg retired.

He had spent from almost 20 years with the university, including 10 years as head of the zoology department, following 20 years teaching and research at Sydney University.

Grigg was one of the early supporters of sustainable use of kangaroos and crocodiles and was among the pioneers who used technology to remotely gather data on wild animals.

Although no longer teaching, he will continue his association with UQ as an Emeritus Professor and has one final funded project to finish. With colleague Andrew Taylor at UNSW, he is developing a new bioacoustic monitoring system that can capture and automatically catalogue biological sounds of any environment, including underwater.

So, retirement will not mean the end of scientific research for the 65-year old, who whose first experience of the joys of zoology was as an 11 year-old “barefoot kid on a bike” in the Atherton tablelands of North Queensland. There he met a visiting German zoologist, Gerhardt von Frankenberg on a year’s sabbatical, who showed him pond fauna, dissected a cane toad with him, taught him to use a microscope and lent him books, “and showed me you could make a living from animals.”

“I remember with clarity,” Grigg told me, “we looked under a lily pad and found a hydra, then we took a plankton net through the dam and got some copepods and watched the hydra kill and eat them.”

His career in zoology took him far from primitive pond organisms, through fish, amphibians, reptiles, monotremes, marsupials to mammals, and from diving with crocodiles, to flying across central Australia, to climbing Mt Kosciusko tracking echidnas in the snow, tracking camels by satellite, catching alligators in Brazil, and twice exploring the Antarctic.

Along the way, he made some momentous discoveries that changed the way crocodile and echidna physiologies are understood. He also contributed to the development of remote sensing of animals in the field.

With colleague with Laurie Taplin and post-graduate students, he discovered that estuarine crocodiles (Crocodylus porosis) have salt glands under their tongues and very specialised hearts. He had first worked with crocodiles under the famous Professor Harry Messel of Sydney University, capturing saltwater crocs at Maningrida, on the Arnhem Land coast, where the common estuary of the Liverpool and Tomkinson River flows into the Arafura Sea.

Although Grigg had originally planned to study thermoregulation in crocodiles, he soon became fascinated by the problem of crocodiles living in a gradient from pure saltwater to pure freshwater. It had been speculated crocodiles must have salt glands to act as built-in desalinators, but no-one had discovered them.

The crocodiles were tagged with radio transmitters and later with injections of radioactive isotopes in saline. To catch the smaller crocs – the large ones were not suitable specimens – they first used spotlights and small harpoons, but soon learned that the full-frontal approach was more effective. Wearing a wetsuit, Tamplin would simply dive off the boat onto the crocodile and wrestle it aboard.

It took nine years of capturing and tagging crocs and searching all over their bodies, as well considering other factors such as diet as a mechanism to manage the salt, but in 1980, Griggs and Taplin identified the sublingual salt glands that enable estuarine crocs to maintain their homeostasis.

Later, still thinking about thermoregulation, this time in monotremes, he investigated snow echidnas with colleagues Mike Augee and Lyn Beard. Short-beaked echidnas (Tachyglossus aculeatus) can be found all over Australia, in deserts, wet and dry sclerophyll forests and rainforests, and even in alpine areas.

“Since birds and mammals evolved from reptiles, they developed endothermy and do not need to rely on behaviour to regulate their body temperature as reptiles do. But what about monotremes?” he said. Echidnas were not supposed to hibernate like mammals – so how did they survive in the snow?

Using tiny radio transmitters surgically implanted into the abdomens of several echidnas above and below the snowline in Mt Kosciusko National Park, Beard, Augee and Grigg were able to remotely record and analyse changes in the animals’ temperature over several weeks, during summer and again in winter, when external temperatures fell below zero.

In 1987, after discovering an echidna apparently in torpor with a body temperature just above 9 degrees C, they were able to track its movements and temperature fluctuations, using recording equipment positioned on rocks or under trees in deep snow, with aerials positioned in the trees to catch the signals emanating from the echidna’s abdomen.

With the readings from this individual, E10, and several others above and below the Kosciusko snowline, they were able to prove that snow echidnas do hibernate. The animals hibernated for periods of about two weeks at a time, when their temperature dropped to about 10 degrees C, the ambient temperature of their burrow, interspersed with periods of one or two days when their temperature rose briefly into the low 30s. Echidnas mate in mid-winter.

The results of the Kosciusko echidna experiments were published in a paper, ‘The Evolution of Endothermy and Its Diversity in Mammals and Birds’ in Physiological and Biochemical Zoology in 2004, which Grigg says is leading to new thinking about how endothermy evolved.

Grigg has long been interested in the management of kangaroos, from his early days of working with the late Dr Graeme Caughley on aerial surveys of kangaroos across central Australia. At first just ‘the pilot’ for the surveys, he soon became involved with the science of kangaroo population ecology and more particularly the politics of kangaroo harvesting.

He has been a vocal advocate of the use of kangaroos as “sheep replacement therapy for rangelands” for many years, and in 2002 contributed a paper on the conservation benefits from harvesting kangaroos, included in a publication by the Royal Zoological Society of NSW, ‘A Zoological Revolution. Using native fauna to assist in its own survival’. He says he hopes the paper will stimulate discussion and further research into sustainable kangaroo management programs.

Known for his hands on approach to research, often involving dangerous activities in the field, Grigg is frequently asked by students how to become a zoologist. “It must look a very interesting life, when you condense all the adventures, excitement and travel into one long story,” he says.

“But the adventures were interspersed with long periods of pedestrian stuff – administration, lecturing and supervising post-graduate students.

Gordon Grigg with students.
Professor Grigg talks to undergraduate students on a field trip

“The real adventure is discovery. There’s probably only 100 people in the world who really care about how a crocodile heart works but it’s still very satisfying to nut it out.”

He admits the crocodile is his favourite animal. “It’s just so utterly spectacular, so long-lived and patient.” He is just about to complete a book on crocodiles – tentatively titled ‘How crocodiles work’, which he says will be “an accessible, well illustrated scientific read sprinkled with personal anecdotes.

“It’s not a text book. I hope it will be useful to anyone with an interest in crocodiles and biology in general.”

And his final word to animal researchers: “Get out in the field and use your best tool – your curiosity.”

©Sue Cartledge

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