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โครงการรวบรวมและจัดทําเอกสารวารสารอิเล็กทรอนิกส์ มหาวิทยาลัยเกษตรศาสตร์

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To determine what amphibians eat, researchers try to use various methods and analyses to obtain
their results (e.g., Solé et al., 2005; Chuaynkern et al., 2009; Camera et al., 2014; Ponpituk et al.,
2015; Goldberg et al., 2018). Based on the items that we presently know that amphibians eat, we
are still far from fully understanding their complete diets because what is known is mainly based on
the diets of adult (or juvenile) amphibians.

In amphibian tadpoles, food is very important for development (Kupferberg, 1997; Alford,
1999), which influences the size and shape of the tadpoles. However, little information about their
food items has been published. Unlike the adult amphibians, the tadpoles generally feed on fungi,
viruses, bacteria, algae, protists, helminths, plant cells, and on other tadpoles (Kupferberg et al.,
1994; Hoff et al., 1999; Goldberg et al., 2018). Moreover, cannibalism in anuran larvae are also
reported in several species (see e.g., Heusser, 1970; Jungfer & Schiesari, 1995).
Approximately 178 amphibian species are known in Thailand, which is 10% of the known global
species (Frost, 2018; Phusaensri et al., 2018). Among them, only some anuran species have had their
food items reported on in detail (Chuaynkern et al., 2009; Ponpituk et al., 2015). However, for the

tadpoles of the amphibians, almost nothing is known about their food items. Therefore, this present
work has reported on the prey items of 18 anuran tadpoles based upon specimens collected from
five localities of Thailand.

MATERIALS AND METHODS

From the following five localities in Thailand (Figure 1), the tadpole specimens were collected

from nature by using dip-nets: Phu Kradueng National Park (Loei Province), Yoddom Wildlife Sanctuary
(Ubon Ratchathani Province), Phu Khiao Wildlife Sanctuary (Chaiyaphum Province), Umphang Wildlife
Sanctuary (Tak Province), and Nam Nao National Park (Phetchabun Province). The tadpoles were
euthanized using 70% ethyl alcohol and were later preserved in a mixture solution of 10%
formaldehyde and 70% ethyl alcohol at a ratio of 1:1 (followed Inthara et al., 2009). These tadpoles
(Table 1) were catalogued and deposited in the Khon Kaen University Vertebrates Collection (KKUC)
in Khon Kaen Province in northeastern Thailand. The identification of tadpoles was made by
comparing the samples to relevant taxonomic works (Inthara, 2000; Grosjean et al., 2003, 2015;
Taksintum, 2003; Meewattana, 2005; Stuart et al., 2006; Danisawat et al., 2010; Aran et al., 2012;

Kaewtongkum et al., 2014a,b; Chuaynkern et al., 2017; Thongproh et al., 2018).
The developmental stages of the tadpole specimens were determined according to the work
of Gosner (1960). In order to investigate the stomach contents, tadpoles were selected, which were
between Gosner’s stages of 31 to 39. Preparation of semi-permanent slides was modified from the
protocol proposed by Somnark et al. (2011). The gut was excised by opening the tadpoles’ bellies
using a surgical scissors. Later, the gut was opened, and all of the stomach contents were removed
and placed into a Petri dish to which 70 % ethyl alcohol was added to preserve them. Then using a

dropper was used to collect the solution of stomach contents, one drop was placed on the slide
along with one drop of glycerin. Finally, the slide was covered with a cover slip and was sealed with
nail polish at the edges of the cover slip. The stomach contents found on the semi-permanent slide
were identified under a compound microscope (Zeiss) at 10x and 40x. Photographs were taken of all

วารสารสัตว์ป่าเมืองไทย ปีที่ 25 พ.ศ. 2561 Journal of Wildlife in Thailand Vol. 25, 2018