Comparative Morphological Analysis of Perinereis sp., Holothuria scabra, and Holothuria fuscocinerea in the Intertidal Zone of Ngentup Beach, South Malang Analisis Morfologi Komparatif Perinereis sp., Holothuria scabra, dan Holothuria fuscocinerea di Zona Intertidal Pantai Ngentup, Malang Selatan

Abstract

Coastal ecosystems are dynamic and productive environments that provide important habitats for benthic organisms, which play essential roles in sediment stabilization and maintaining ecosystem balance. Morphological characteristics can reflect adaptive responses of benthic organisms to environmental conditions, particularly in intertidal zones influenced by tidal fluctuations and habitat heterogeneity. This study aimed to describe and compare the morphological characteristics and relatedness of Perinereis sp., Holothuria scabra, and Holothuria fuscocinerea found in the intertidal zone of Ngentup Beach, South Malang. The study was conducted in November 2025 using a quantitative descriptive survey approach. Data were collected through direct observation of external morphological characters using the Operational Taxonomic Unit (OTU) method. Data tabulation and binary coding were performed using Microsoft Excel, while similarity analysis and dendrogram construction were carried out using PAST version 5.2.1. The results showed clear morphological differences among the three species. Perinereis sp. exhibited segmented body structures, parapodia, setae, bilateral symmetry, and hydrostatic skeletons. In contrast, Holothuria scabra and Holothuria fuscocinerea showed unsegmented bodies, tube feet, oral tentacles, secondary radial symmetry, and calcareous endoskeletons. Similarity analysis showed the highest similarity value (88%) between Holothuria scabra and Holothuria fuscocinerea, while the lowest similarity value (16%) was found between Perinereis sp. and Holothuria fuscocinerea. The dendrogram indicated that the two Holothuria species formed the closest morphological cluster, while Perinereis sp. was separated in a different cluster. This study provides important baseline data for benthic organism monitoring in coastal ecosystems, although the limited sample size remains a limitation of this study.