This monograph includes seven chapters, each presenting recent advancements in the field of marine biology. Chapter One describes how the biodiversity of the Mediterranean marine environment has changed due to climate change and species invasions and proposes policy suggestions. Chapter Two discusses an integrated ecotoxicological view on elasmobranch conservation regarding chemical contamination alongside potential ecological outcomes for this group and human impacts derived from elasmobranch consumption. Chapter Three congregates information about the morphological traits of crabs to lay a foundation for a better understanding of taxonomic and phylogenetic studies, ecological studies, and the stock assessment and management of commercially important species. Chapter Four shows how foraminiferal associations are influenced by nutrients and abiotic factors that control the carbonate production in the modern outer shelf of Rio Grande do Norte, in the region of Açu Reefs. Chapter Five describes the first satellite tagging research project in the southern Gulf of Mexico for bottlenose dolphins. Chapter Six investigates the threat posed by cutaneous fibropapillomatosis, a tumor that arises on the skin or internal organs of sea turtles and affects up to 97% of this population. Finally, Chapter Seven discusses the eco-biology, exploitation and social aspects related to the common octopus along the Kerkennah Island in the South Center of the Mediterranean Sea.