Article history: ©2018 at http://jfmr.ub.ac.id Diterima / Received 01-04-2018 Disetujui / Accepted 13-07-2018 Diterbitkan / Published 21-07-2018 KARAKTERISTIK HABITAT DAN KELIMPAHAN UNDUR-UNDUR LAUT (HIPPOIDEA) DI PANTAI PURWOREJO Oki Trian Nugraha a , Suryanti a, * dan Siti Rudyanti a a Program Studi Manajemen Sumberdaya perairan, Departemen Sumberdaya Akuatik, Fakultas Perikanan dan Ilmu Kelautan, Universitas Diponegoro, Semarang, Indonesia *Correspondent Author : oki.trian1945@g ma il.co m Abstrak Undur-undur laut atau kepiting pasir merupakan hewan bentik dari superfamili Hippoidea yang hidup di pantai berpasir. Persebaran Undur-undur berpotensi ditemukan di pantai pesisir Purworejo. Undur-undur laut memiliki manfaat ekonomis dan peranan ekologis pada ekosistem pantai. Tujuan penelitian ini adalah untuk mengetahui karakteristik habitat dan kelimpahan Undur-undur laut di pantai Purworejo serta untuk mengetahui hubungan variabel karakteristik habitat dengan kelimpahan Undur-undur laut. Penelitian dilaksanakan pada bulan Desember 2017 di pantai Jatimalang, pantai Malang dan pantai Ketawang kabupaten Purworejo. Metode yang digunakan dalam penelitian ini adalah metode survey yang bersifat deskriptif. Pengambilan data karakteristik habitat (kemiringan pantai, warna sedimen, bahan organik sedimen, ukuran butir sedimen, variabel umum) dan kelimpahan Undur-undur laut dilakukan dengan menggunakan tiga kuadran transek seluas 10x10 meter ditempatkan di aera swash zone. Hasil penelitian menunjukkan karakteristik pantai yang dihuni Undur-undur laut di pantai Purworejo memiliki tipe landai, lebar swash zone sebesar 12 – 23 meter, warna substrat pasir berwarna hitam sampai hitam keabu-abuan, bahan organik sedimen tergolong sangat rendah dan memiliki ukuran rerata butir sedimen di dominansi oleh pasir halus dan pasir sedang (0,5 – 1mm). Jenis Undur-undur laut yang ditemukan di pantai Purworejo yaitu Emerita emeritus, Hippa adactyla dan Albunea symmysta , dengan kelimpahan 32 - 51 ekor/100 . Hasil analisis regresi linier menunjukkan bahwa ukuran rerata butir sedimen memiliki hubungan linier negatif dengan kelimpahan Undur-undur laut, artinya semakin bertambahnya ukuran rerata butir sedimen akan berbanding terbalik dengan kelimpahan Undur-undur laut. Kata Kunci : Habitat karakteristik, Kelimpahan Undur-undur laut, Pantai Purworejo Abstract Mole crabs is a benthic animals of the Hippoidea superfamily that live on sandy beaches. The distribution of Mole crab in Indonesia is potentially found on the Purworejo beach. Mole crabs have economic benefits and ecological roles in beach ecosystems. The research aims to know habitat characteristic and abundance of Mole crabs in Purworejo beach and to know relation of habitat characteristic variable with Mole crabs abundance. The research was conducted during December 2017 in Purworejo beach. Data collection of habitat characteristics (beach slope, sediment color, sediment organic material, sediment grain size, general variables) and abundance of Mole crabs were conducted using three 10x10 meter transect quadrants placed in the swash zone area. The results showed that the characteristics of mole crab habitat in the coast of Purworejo have a sloping beach and swash zone width of 12-23 meters with the color of black to grayish black sand substrat,the sediment organic material is very low and has the average size of the dominant sediment grains by fine sand and moderate sand (0.5 - 1mm). The consist of mole crabs in the Purworejo beach are Emerita emeritus, Hippa adactyla and Albunea symmysta with an abundance of 32-51 individual/100 . The results of linear regression calculations showed that the average sediment grain size has a negative linier relationship to the abundance of mole crab, it means that increasing the average size of sediment grains will be inversely proportional to the abundance of Mole crabs. Keywor ds : Abundance of Mole Crab, Habitat characteristic, Purworejo beach