Ikan hiu martil merupakan salah satu spesies hiu dengan bentuk kepala khas menyerupai palu dan dikenal sebagai predator puncak dalam ekosistem laut. Keberadaannya penting dalam menjaga keseimbangan rantai makanan, namun populasinya terancam akibat eksploitasi berlebihan. Penelitian ini bertujuan mengidentifikasi jenis dan karakter molekuler hiu martil (Sphyrna sp.) dari perairan Tanah Kuning, Kabupaten Bulungan, Kalimantan Utara, menggunakan pendekatan morfologi dan molekuler melalui metode DNA barcoding. Penelitian dilaksanakan dari Desember 2024 hingga Maret 2025 dengan metode purposive sampling, melalui pengambilan lima spesimen hiu martil menggunakan pukat hela. Identifikasi dilakukan melalui dua pendekatan, yaitu: (1) analisis morfologi termasuk morfometri di antaranya karakter panjang total, panjang kepala, dan bentuk sirip; dan (2) analisis molekuler melalui tahapan ekstraksi DNA, pengukuran kemurnian, amplifikasi gen COI mitokondria dengan PCR, elektroforesis, dan sekuensing DNA. Validasi genetik dilakukan dengan analisis BLAST dan perhitungan jarak genetik menggunakan model Tamura 3-Parameter. Hasil identifikasi morfologis menunjukkan seluruh sampel memiliki ciri khas spesies Sphyrna lewini. Validasi molekuler melalui BLAST menunjukkan tingkat kemiripan 99,54–100% dengan data GenBank untuk Sphyrna lewini, dan analisis jarak genetik mengindikasikan kekerabatan yang sangat dekat antarindividu. Penelitian ini membuktikan bahwa DNA barcoding efektif untuk identifikasi spesies hiu martil dan berpotensi mendukung konservasi serta pengelolaan sumber daya hiu secara berkelanjutan di perairan Tanah Kuning.
Kata kunci: COI, DNA Barcoding, Filogenetik, Sphyrna lewini ,Tanah Kuning

Hammerhead shark is a species of shark with a distinctive hammer-like head shape and it is known as a top predator in the marine ecosystem. Its existence is important in maintaining the balance of the food chain, but its population is threatened by excessive exploitation. The purpose of this study was to identify the types and molecular characteristics of hammerhead sharks (Sphyrna sp.) from the waters of Tanah Kuning, Bulungan Regency, North Kalimantan, using morphological and molecular approaches through the DNA barcoding method. The study was conducted from December 2024 to March 2025 through a purposive sampling method, by taking five hammerhead shark specimens using a trawl. Identification was carried out through two approaches: (1) morphological analysis including morphometric including total length, head length, and fin shape; and (2) molecular analysis through the stages of DNA extraction, purity measurement, and mitochondrial COl gene amplification with PCR, electrophoresis, and DNA sequencing. Genetic validation was carried out using BLAST analysis and genetic distance calculations using the Tamura 3-Parameter model. The results of morphological identification showed that all samples had the characteristics of the Sphyrna lewini species. Molecular validation through BLAST showed a similarity level of 99.54-100% with GenBank data for Sphyrna lewini, and genetic distance analysis indicated a very close relationship between individuals. This study proved that DNA barcoding was effective for identifying hammerhead shark species and had the potential to support conservation and sustainable management of shark resources in Tanah Kuning Keyword: COI, DNA Barcoding, Phylogenetik, Sphyrna lewini ,Tanah Kuning