The spiny turtle is a medium-sized tortoise with a brown shell and red-spotted head.[4] Also known as the “cog-wheel turtle,” it derives its name from its spiky-edged carapace, marginal scutes, and spiny keel.[5][6][7] As juvenile spiny turtles become adults, the black striped and yellow underside of their shell fades in color.[5] In addition, the juveniles’ serrations, or jagged edges, at the carapace margin decrease in size and become restricted to the carapace’s rear margin.[8] These changes of the spine and carapace serve as evolutionary adaptations attempting to prevent predators from preying on juvenile turtles.[6]
Taxonomy
The spiny turtle belongs to the kingdom of Animalia, the order of Testudines, and the genus of Heosemys.[9] The classification of Heosemys incorporates four species: Heosemys annandalii, Heosemys depressa, Heosemys grandis, and Heosemys spinosa; however, relationships between the four are undetermined.[10] Variation among the Heosemys spinosa is also uncertain, but it has been suggested that there are two types: a “mainland form” dwelling in Malaysia, Thailand, and southern Myanmar, and an “insular form” found in Indonesia and the Philippines, possibly in Brunei and Singapore as well.[10]
Anatomy
Adult spiny turtles’ carapace length usually falls between 175 mm to 220 mm and their mass ranges from 1.5 kg to 2.0 kg.[7]
Behavior
The spiny turtle buries itself in leaf litter to camouflage during the day and only emerges at night, foraging for food.[4][6]
While often portrayed as a herbivore, the spiny turtle also eats carrion and insects alongside fruits and plants.[4] Fruit from the yin-ngan tree is especially important for the turtle, and in Myanmar, the turtle often dwells beneath these trees when the trees are fruiting.[11] Similarly, captive juvenile spiny turtles consume fruit salads multiple times a week, particularly those containing tomatoes.[7] At the Kubah National Park in Sarawak, analysis of fecal content revealed the turtles’ role as seed dispersal agents, for their fecal matter contained five different seed types.[12] Arthropods and hair were also found in the samples, suggesting consumption of mammals and other animals.[12]
young spiny turtle
Reproduction
Mating occurs in December and February, and appears to be triggered by rain.[7] Regarding nesting behavior in the wild, the female lays one or two eggs in a nest and produces up to three clutches annually.[7]
In captivity, it has been observed that spraying males with water results in them chasing females and attempting to mount.[7] To ease the delivery of the egg, a hinge forms in the female turtle’s plastron before it is laid.[13] The egg is usually covered with a partial layer of substrate, and researchers have found eggs laid in a so-called “protected spot” underneath cork bark or thick foliage.[4]
Many attempts at reproduction in captivity have proved unsuccessful due to the eggs’ shells being thick and prone to bursting if the substrate is too damp.[4] The first successful copulation in captivity occurred in 1991 at Zoo Atlanta, where incubation lasted for 106 days in a medium of peat moss, long fiber peat moss, and damp sand.[7] For the first 35 days, the egg was incubated at a temperature of 28-30°C, and for the last 71 days, the temperature was decreased to 26-28°C.[7]
Labeled as “vulnerable” by the IUCN in 1996, the spiny turtle became endangered in 2000 when the supply of the species declined by a half in the Chinese food market.[4] It is suggested that the main threat to the spiny turtle has been the destruction of natural forests to create oil palm plantations, common in southern Myanmar.[11] The spiny turtle’s participation in the international pet trade and its use in traditional Chinese medicine has also led to its decline.[4] However, numerous conservation efforts have been undertaken because the turtle is protected by the Philippines Wildlife Act and other initiatives.[6][15] A spiny turtle hatching at the Chester Zoo in the UK in 2013 has also given hope to conservationists that the species may be retained.[16]
^ abcdefghGoetz, Matthias. "Husbandry and breeding of the spiny turtle Heosemys spinosa (Gray, 1931) at the Durrell Wildlife Conservation Trust." Radiata, vol. 16, no. 2, 2007, pp. 1-15. Heosemys Spinosa. Mar 16, 2022.
^ abSpinks, Philip Q., et al. "Cryptic variation and the tragedy of unrecognized taxa: the case of international trade in the spiny turtle Heosemys spinosa (Testudines: Geoemydidae)." Zoological Journal of the Linnean Society, vol. 164, no. 4, 2012, pp. 811-824, doi:10.1111/j.1096-3642.2011.00788.x.
^ abPlatt, Kalyar, Steven G. Platt, and Thomas R. Rainwater. "First Record of the Spiny Turtle (Heosemys spinosa) in Myanmar." Chelonian Conservation and Biology, vol. 13, no. 2, 2014, pp. 257-260. Agriculture Science Database, Environmental Science Database, ProQuest Central.
^ abBaizurah, Siti N., and Indraneil Das. "Heosemys Spinosa (Spiny Hill Turtle)." Herpetological Review, vol. 51, no. 4, 2020, pp. 831-832.
^Fritz, Uwe; Peter Havaš (2007). "Checklist of Chelonians of the World" (PDF). Vertebrate Zoology. 57 (2): 224–225. ISSN 1864-5755. Archived from the original (PDF) on 1 May 2011. Retrieved 29 May 2012.
^ abDiesmos, Arvin C., et al. "Status and Distribution of Nonmarine Turtles of the Philippines." Chelonian Conservation & Biology, vol. 7, no. 2, 2008, pp. 157-177, doi:10.2744/CCB-0672.1.
^"Spiny turtle hatching is first for UK." Western Mail, 2013, pp. 13. ProQuest Central.
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