Dugong dugon

Most living and fossil sea cows of the subfamily Dugonginae (Dugongidae, Sirenia, Mammalia) are characterized by large upper incisor tusks, which are thought to play an important role (at least primitively) in feeding on seagrass rhizomes. Testing this hypothesis is difficult, because the only extant tusked sirenian (Dugong dugon) is morphologically and perhaps behaviorally aberrant. The tests attempted here involve examination of stomach contents of wild Recent dugongs, experiments using plastic replicas of diverse tusks to harvest seagrasses, gross anatomical observations on tusks and skulls, measurements of tusk tip geometry, and observations of microwear on tusks. We conclude that (a) male D. dugon (with erupted tusks) do not consume more rhizomes than females (without erupted tusks); (b) the tusks do not play a significant role in feeding in the modern dugong; (c) larger, more bladelike tusks are more effective at harvesting rhizomes, but the effect of shape was not experimentally separated from the effect of exposed tusk length; (d) some fossil dugongines show apparent cranial adaptations for downward and backward cutting motions of their large, bladelike tusks; (e) geometry of wear surfaces is consistent with use of at least the more bladelike tusks as cutting instruments; (f) preliminary observations of microwear in D. dugon do not indicate more than occasional use of the tusks in purposeful harvesting of rhizomes, and then only opportunistically by large adult males. The hypothesis of such tusk use by extinct dugongines (in contrast to the living species) is so far corroborated, but available data and tests do not suffice to establish this conclusively. Anat Rec, 290:523–538, 2007. © 2007 Wiley-Liss, Inc.

Dugong adalah mamalia laut milik Sirenia dengan nama ilmiah Dugong
Dugon atau sering juga disebut sebagai sapi laut yang berstatus hukum sebagai hewan yang dilindungi di Indonesia. Di Pulau Bintan kasus penemuan dugong sering terjadi. Kondisi ekosistem perairan dengan hamparan vegetasi lamun mendukung kelangsungan hidup mamalia herbivora seperti Dugong. Tujuan dari penelitian ini adalah melakukan
pemodelan spasial untuk mengetahui sebaran habitat dugong dengan menggunakan beberapa variabel lingkungan yang terjadi di ekosistem laut yang menjadi indikator penilaian penunjang keberlangsungan hidup dugong. Metode yang digunakan adalah analisis spasial raster untuk perancangan variabel lingkungan yang meliputi naturalized Euclidean distance, dan Maximum Entropy. Berdasarkan hasil kajian, nilai AUC
pemodelan adalah 0.96 dengan nilai deviasi 0.04, sedangkan distribusi wilayah yang berpotensi untuk sebaran habitat dugong di beberapa perairan Pulau Bintan yaitu Desa Berakit, Gunung Kijang, Kawal, dan Malang Temu. Parameter yang paling berpengaruh dalam pemodelan sebaran potensi habitat dugong ini adalah padang lamun, jarak dari
sungai, dan kedalaman laut. Habitat yang sangat mendukung kehidupan dugong ini didominasi oleh vegetasi tutupan lamun yang merupakan sumber makanan utama dugong.

Dugong populations are decreasing worldwide due to human activities. Reproductive behaviour observations are valuable due to the scarce information on dugong reproductive behaviour, which vary between populations. Surveys were carried out to document dugong reproductive behaviour at the island of Koh Libong, province of Trang, Thailand. Aerial images of dugong reproductive behaviour were captured using a zoom camera mounted on a drone. Images clearly revealed several stages of matting (following, approaching and stimulating, pairing, mounting and separating). In addition, we also identify a possible method to track individual dugongs by recording the tusk scars in dorsal regions using drone images. This study highlights the importance of small quadcopter drones as a cost-efficient tool to document dugong behaviour such as mating, identification of individuals, measurement of body mass index, contributing to an effective conservation effort.