ABSTRAKAnalisis sebaran ukuran adalah salah satu metode yang dapat dijadikan acuan dan umum digunakan untuk mengetahui perubahan pola pertumbuhan kerang bulu. Perbandingan antara pertumbuhan dimensi spesies terkait atau spesies yang sama di habitat berbeda menggunakan hubungan morfometrik (dimensi cangkang). Tujuan penelitian ini yaitu mengetahui kepadatan, sebaran ukuran, pola pertumbuhan, faktor kondisi kerang bulu (Anadara antiquata), kualitas perairan serta kerapatan lamun di perairan Kei Kecil. Penelitian dilaksanakan pada 2 lokasi yaitu perairan Letman dan Yatwav. Metode pengambilan sampel menggunakan purposive sampling. Kepadatan Letman diperoleh nilai sebesar 10,6 ind/m2 sedangkan di perairan Yatwav sebesar 5,7 ind/m2. Ukuran panjang cangkang di perairan Letman berkisar antara 2,70-7,28 cm, lebar cangkang 2,10-6,41 cm, tinggi cangkang 1,80-5,39 cm dan 10,10-150,31 gr sedangkan ukuran panjang cangkang di perairan Yatwav berkisar 1,80-5,03 cm, lebar cangkang 1,60-6,45 cm, tinggi cangkang 1,30-4,35 cm dan berat total cangkang 21,20-77,46 gr. Hubungan panjang-berat kerang bulu perairan Letman dengan persamaan y = 1,1842x2,173 sedangkan perairan Yatwav dengan persamaan y = 3,3331x0,8371 sehingga memiliki pola pertumbuhan allometrik negatif (b3). Hasil analisa faktor kondisi diketahui nilai faktor kondisi perairan Letman sebesar 1,29 sehingga tergolong agak pipih sedangkan nilai faktor kondisi perairan Yatwav sebesar 3,86 sehingga tergolong gemuk/montok. Kisaran suhu pada kedua lokasi penelitian berkisar 29-33°C, salinitas berkisar 26-35 ‰, pH berkisar antara 7,2-8,2 dan DO berkisar 5-6,7 mg/l. Kerapatan lamun tertinggi adalah spesies Thalassia hemprichii dengan nilai kerapatan sebanyak 29 ind/m2 di perairan Letman sedangkan sebanyak 47 ind/m2 di perairan Yatwav.Kata kunci: Ukuran, Pertumbuhan, Lamun, Kei kecilABSTRACTSize distribution analysis is one method that can be used as a reference and is commonly used to determine changes in growth patterns of feather clams. Comparison between growth dimensions of related species or the same species in different habitats using morphometric relationships (shell dimensions). The aim of this research is to determine the density, size distribution, growth patterns, condition factors of feather clams (Anadara antiquata), water quality and seagrass density in Kei Kecil waters. The research was carried out at 2 locations, namely Letman and Yatwav waters. The sampling method uses purposive sampling. The Letman density obtained was 10.6 ind/m2, while in Yatwav waters it was 5.7 ind/m2. The length of shells in Letman waters ranges between 2.70-7.28 cm, shell width 2.10-6.41 cm, shell height 1.80-5.39 cm and 10.10-150.31 gr while the length shells in Yatwav waters range from 1.80-5.03 cm, shell width 1.60-6.45 cm, shell height 1.30-4.35 cm and total shell weight 21.20-77.46 gr. The length-weight relationship for feather clams in Letman waters is with the equation y = 1.1842x2.173, while in Yatwav waters is with the equation y = 3.3331x0.8371 so it has a negative allometric growth pattern (b3). The results of the condition factor analysis show that the condition factor value of the Letman waters is 1.29, so it is classified as slightly flat, while the condition factor value of the Yatwav waters is 3.86, so it is classified as fat/plump. The temperature range at the two research locations is around 29-33°C, salinity is around 26-35‰, pH is between 7.2-8.2 and DO is around 5-6.7 mg/l. The highest density of seagrass is the species Thalassia hemprichii with a density value of 29 ind/m2 in Letman waters while as much as 47 ind/m2 in Yatwav waters.Keywords: Size, Growth, Seagrass, Kei kecil