I. Introduction
The exploration of underwater environments has been an active engagement across a plethora of scientific fields, such as ocean ecology, marine geological sciences, and natural resources discovery. Recently, visually guided underwater robots and intelligent underwater monitoring systems become instrumental tools or equipment to assist these activities effectively, and many image processing algorithms have been developed to serve various purposes. However, existing solutions for conducting marine scene parsing and object segmentation are largely underexplored. In this article, it is our great interest in developing image segmentation algorithms to perform marine animal segmentation (MAS), particularly for a highly ill-conditioned underwater environment.