# Chemical Defenses in Medusozoa

## TL;DR

This paper reviews non-toxin-based chemical defenses in Medusozoa, highlighting their potential for biotechnology and ecology.

## Contribution

The paper compiles and organizes scattered information on Medusozoa's non-toxin defenses, emphasizing antimicrobial activities and potential biotechnological applications.

## Key findings

- Antimicrobial activities are the most studied and potentially exploitable defense in Medusozoa.
- Some Medusozoa species studied as model organisms may share defensive strategies with related classes.
- Integrated understanding of Medusozoa defenses can inform both ecological frameworks and biotech applications.

## Abstract

Cnidarian defensive strategies are commonly associated with the toxins they synthesize. Because toxins have negative, sometimes lethal, effects on humans, research has focused on them for medical and biotechnological applications. However, Cnidaria possess a variety of defensive systems complementing toxins. In recent decades, ecological and biotechnological studies have shed light on these systems, particularly in Anthozoa, while the knowledge of defensive systems different from toxins has remained limited in Medusozoa (Cubozoa, Hydrozoa, Scyphozoa and Staurozoa). In this review, we collected the scattered information available in the literature and organized it into four main topics: UV-light protection compounds, antioxidants, antimicrobial peptides, and endosymbionts. Within the topics, we found the largest amount of data refers to antimicrobial activities, which suggests this line of research as a potential exploitation of this group of organisms often appearing in large aggregates. We also found that some Medusozoa have been studied in detail as model organisms, although the close phylogenetic relationship among classes suggests that some defensive strategies may be common to other members of different classes. Indeed, an integrated understanding of defensive systems has the potential to inform not only ecological and evolutionary frameworks, but also biotechnological applications—from the identification of novel antioxidants or antimicrobial agents to the valorization of Medusozoan biomass.