Animal Forests of the World: An Overview

In the marine benthos, megabenthic communities dominated by sessile suspension feeders (such as sponges, corals, and bivalves) form three-dimensional structures which provide architectural complexity and shelter for several species. These communities are, in part, structurally and functionally similar to the terrestrial forests, with the main difference that they are dominated by animals instead of plants. The term “animal forests” has been introduced to describe these communities, highlighting the structural and functional similarities with their terrestrial counterparts trying to gather, in a single concept, all the three-dimensional alive structures dominated by sessile animals. Among the animal forests, tropical coral reefs, due to their high biodiversity, have been defined as the “rainforests of the sea” and have attracted the interest of scientists all over the world. However, during the last decades, many other animal forests have been subjected to the attention of the scientific community; Cold-water coral communities, with their key role in ecosystem functioning, fisheries sustainability, and potential carbon sinks in deep benthic ecosystems, are an example of other animal forests that probably cover larger extensions than the tropical shallow coral reefs, but for which the distribution and fully understanding of their functionality are still largely unknown. Similarly, recent technological advances have allowed scientists to explore the mesophotic environment, revealing complex and unknown animal forests in the so-called twilight zone. Gradually, we begin to understand the real extension of these threedimensional benthic communities and their ecological importance. The animal forests are probably one of the most widely distributed ecosystems on the planet, due to the wide spectra of environments they occupy, from the shallow mussel beds to the tropical and the deepest cold-water coral communities or Antarctic sponge grounds. However, during the last 20 years or so, there has been an increasing evidence of important changes in marine ecosystems due to human-induced disturbances, which are dramatically reducing biodiversity, biomass, and the potential recover of the animal forests all over the world. Many aspects related to the occurrence, distribution, life history, population dynamics, trophic ecology, or physiology of the organisms which structure these communities still need to be understood in order to get an insight into their functional ecology and dynamics. The concept of animal forests imply a holistic approach allowing the pooling of different ecosystems under the same umbrella and possibly lead to a better understanding of their ecological role and the application of effective management and conservation measures.