Emydura subglobosa, hatchling. Photograph by Ellen Nicol
Most of the water turtles (called "tortoises" in Australia) of the Australasian area fall into one of two categories: the snake-necked species and the short-necked species. Having specialized in these turtles for over 20 years, I still find them some of the most desirable turtles to keep if you fancy aquatic species. Species native to Australia exclusively are not available for legal import because Australia does not permit export of or trafficking in any of its native fauna. Species whose range extends outside of Australia, such as Emydura subglobosa and Chelodina novaeguineae, are occasionally imported. Our groups of these species breed regularly.
Emydura subglobosa (or in some reference works E. albertisii) is one of the Australasian short-necked species. Confusion exists over the taxonomy of reptiles of the region, and I understand that many of the reptiles are being reclassified after many years of study by biologists, but complete information has not yet become available.
The carapace of this appealing side-necked turtle is a medium to charcoal gray color with no design. The plastron bridge and underside of the marginal scutes have a striking lighter gray and coral pink design which does not fade as the animal matures. The head is dark gray with a yellow stripe behind the eye, and there is a bright coral design under the bottom jaw. The male is smaller than the female, and he has a more elongated tail. Adult size usually does not exceed 8-9 inches, and they breed readily in captivity. (Note the final paragraph herein!)
Emydura subglobosa will eat almost anything: worms, lean beef, chicken livers/hearts, fish, Trout Chow, as well as the occasional piece of banana (banana will foul the water rather quickly), various greens such as Romaine lettuce, escarole, and slivers of zucchini squash. A calcium block, which you can make from plaster of Paris mixed with water and dried, should be in their water at all times.
These turtles are highly aquatic and rarely leave the pond except to bask or nest. They are inveterate baskers, and will perch by the hour in the sunshine or under a heat lamp. Outdoors, they are the first ones sunning in the morning, and the last ones to return to the water at dusk. Indoors, they will bask in the beam of a 75-watt spotlight, but natural sunlight (not passed through glass) is better for them. If you cannot provide natural sunlight, an overhead Vita-lite lamp (which provides wide-spectrum light) should be used as well as the incandescent bulb. Cork bark, plastic greenery or ramps of some kind should be provided to enable the turtles to climb out of the water or to be supported when they sleep at night.
In Florida we are able to keep most of our turtles outdoors year around. Emydura subglobosa adults are housed in covered screen-sided pens that are 8' square and 2' high, with a sunken 300-gallon heavy plastic cattle tank sunk to ground level. There are wooden and screen ramps, as well as sunken logs attached to the sides of the tank so they can easily exit the pond. We do not use filters, but the pond water is completely drained frequently or when it is dirty. It is then that we inspect tank occupants for illness or injury.
Reproduction
Over 10 years ago, we acquired 3 juvenile female red-bellied short-necked turtles as mates for our lone juvenile male. The females had lesions over much of their shells, but now the sores are healed and the turtles have turned into perfect adults, reproducing every year since 1987. All of the females produce multiple clutches of eggs, and the nesting season lasts from February to July.
My earlier records were somewhat sketchy, but since 1990, I have kept detailed records on the reproduction of this species. In 1990, 78 eggs were deposited and 58 of these hatched. In 1991, 65 eggs of 76 hatched, and in 1992 we had 81 eggs, 70 of which produced live babies. So for the 3 years, 235 eggs were deposited and 193 hatched. Each year we also found babies that had hatched in the ground, and these figures do not reflect those numbers.
Their nesting behavior is quite different from our other Australasian turtles that will come on land and pace in the grass for up to 2 weeks before finding a spot that suits them. By contrast, the red-bellied short-necked turtles come out on land once or twice--mostly during the night or early morning--and quickly dig shallow nests, often between grass tussocks, which makes eggs harder to locate. The female covers the nest very carelessly, not compacting the soil with her plastron. Often a nest can be spotted by the amount of loose dirt not replaced in digging the nest hole. While snake-necked turtle females can take up to 4 hours to deposit eggs and cover the nest to their satisfaction, E. subglobosa take only about 1 hour from start to finish. Their work shows it when compared to the snake-necked turtles, whose nests are almost impossible to find because they are so well camouflaged.
Records and personal knowledge indicate in which months they usually nest, and I carefully monitor the gravid females for nesting behavior. If I see a gravid female walking around one day, but thereafter remaining in the water, I palpate the inguinal cavities to see if eggs are there. If the female feels "hollow" I dig in the soil until the nest is found.
Nest complement is between 7 and 14 eggs, with 10 being the average. The eggs are hard-shelled, oval-shaped and usually about an inch long. I dig up the eggs with my hands, wash them off, and candle each under a light I have for that purpose. An early sign of viability is the yolk settling to the bottom half of the shell. On several eggs I write the date they were deposited.
I set the eggs, number side up, on damp newspaper crumpled into a small "pad" on the bottom of a clean plastic food container. The size of the container I use depends on the number and size of the eggs, but has to be shallow enough to fit inside the incubator. The eggs should touch each other in a single layer. Another pad of damp newspaper is placed compactly over the top of the eggs. Personally, I do not place lids on the containers, but lids may be used if holes are cut into them for ventilation. I like to use newspaper because moisture can readily be ascertained by the color and stiffness of the paper. If it is stiff and light in color, moisture needs to be added. If it is soft and dark-colored (but not dripping) it is all right. Water should never be added to the bottom newspaper, as the eggs should not sit in free-standing water. A little practice will soon establish the proper moisture limits. Some hobbyists prefer a Vermiculite substrate, but the newspaper base has been most successful for me in the past.
The eggs in their containers are incubated in an electric incubator kept at 81° - 83° F. For this species, at that temperature incubation time is between 42 and 49 days.
The babies hatch in a manner I have not seen in other turtles. The turtle is positioned inside the shell with its head turned to the side and tucked into the axillary hollow (between the neck and front leg). The hatchling must rotate in the shell, when ready to hatch. In doing so, its caruncle (egg tooth) cuts a circular ring all around the shell at the head end. I have seen a nest of hatchling E. subglobosa with most of the eggs with little "flaps" on one end where they have made the initial break. They usually do not hatch immediately, but will sit in the egg peering out of the hole they have made until they feel ready to emerge.
In early September (1992), my husband Bob and I began to find dry newly-hatched babies on the ground in the pen. They were fine and had very little evidence of the umbilical scar. Between us, we found 8 babies--enough to represent a proper clutch. But then, on one rainy day, we began to find more babies that must have hatched later because their umbilical scars were more prominent than those of the first batch. Five babies were found clustered in a corner, but I knew there would be more. I promptly drained the 300 gallon pond to see if any were in the water. I found none, and refilled the pond with water.
After the first hatchlings had appeared in the pen, we both tried (unsuccessfully) to find the empty shells. When the second batch of babies showed up in the pen, I was determined to find the nest. Randomly feeling the soil my fingers sank in a soft spot. After digging there, I uncovered empty shells as well as 5 babies in various stages of emergence. Along with 2 others found in another area, this nest contained 12 babies; all eggs had hatched.
Obviously, while some chelonian eggs do better when hatched artificially, eggs from these Australasian turtles will do all right if left in the ground (at least in Florida). I prefer hatching to occur in the incubator, rather than in the ground where babies can be destroyed by ants, moles, or predation by larger turtles.
An E. subglobosa egg from nest #45 of 6/19/92 was almost a third larger than the other 11 eggs in the nest. This indicated that it would be either an unusually large hatchling or twin embryos. The egg hatched, along with the rest of the clutch, after 46 days; and there were 2 perfectly-formed babies attached at each side of the yolk sac. The normal length of this species' shell as a hatchling is between 25 and 30 mm. At 15 mm long, one of the twins was about half the size of the other, which was of normal size. To my dismay, they both tried to move in different directions which resulted in their connection to the yolk sac being quickly severed. Both swam and walked normally, and I had hopes that both would survive. The smaller twin was kept separate from the others, but it weakened, become less active and died within 10 days of hatching. The remaining twin is now indistinguishable from the other hatchlings of 1992.
While it is fun to have these pretty babies, sometimes I feel like the old woman in the shoe, with so many kids she didn't know what to do. I wish the adults would take a breather for a few years and spare me too much of a good thing.
Ellen Nicol is a long-time member of the California Turtle and Tortoise Club, and served as Editor of the Tortuga Gazette from March 1974 to October 1975.
Originally published in the Tortuga Gazette 29(2): 1-3, February 1993
