Abstract | Abstract. Research on the sponge barnacle of Indonesia is very rare, and this study is aimed to describe the morphological characteristics of sponge barnacles and their specific relationship with their sponge host species. This research was a survey and sponge samples were collected by tearing apart any available sponge found in three sampling locations, typically coral reef areas of Weh Island, Seribu Islands, and Karimunjawa Islands. Sponge barnacles contained in sponge samples were observed using stereo microscope and scanning electron microscope, and species identification was determined based on the morphological description of Darwin (1854), Pilsbry (1916), Martin dan Davis (2001), and Kolbasov (1993). Four species of sponge barnacles were found consisting of Acasta cyathus, Acasta fenestrata, Euacasta dofleini, and Membranobalanus longirostrum. Specific relationships of barnacle and its sponge host were found between Euacasta dofleini and Haliclona sp. and between Membranobalanus longirostrum and Suberites sp. respectively. Keywords : sponge; barnacle; acasta; membranobalanus; biodiversityAbstrak. Penelitian teritip spons Indonesia jarang dilakukan sejak kelompok ini pertama kali dideskripsikan hingga saat ini. Tujuan dari penelitian ini adalah untuk mengkaji karakter morfologi teritip spons Indonesia dan untuk mengkaji hubungan spesies spesifik teritip terhadap spons. Pengambilan sampel pada penelitian ini dilaksanakan sejak Oktober sampai Desember 2012 di tiga lokasi yaitu Pulau Weh, Kepulauan Seribu, dan Kepulauan Karimunjawa. Metode penelitian menggunakan metode survei dan titik pengambilan sampel dipilih berdasarkan keberadaan spons. Sampel diamati menggunakan mikroskop stereo dan mikroskop elektron kemudian diidentifikasi berdasarkan deskripsi Darwin (1854), Pilsbry (1916), Martin dan Davis (2001), dan Kolbasov (1993). Hasil penelitian didapatkan empat spesies teritip spons yaitu Acasta cyathus, A. fenestrata, Euacasta dofleini, dan Membranobalanus longirostrum. Terdapat hubungan spesies spesifik antara teritip dan spons inang yaitu antara teritip E. dofleini dan spons Haliclona sp. dan antara teritip M. longirostrum dan spons Suberites sp. Kata kunci : teritip; spons; acasta; membranobalanus; biodiversitas |