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Echinoderms and sponges share a unique feature that helps them face predators and other environmental pressures. They both possess collagenous tissues with adaptable viscoelastic properties. In terms of morphology these structures are typical connective tissues containing collagen fibrils, fibroblast- and fibroclast-like cells, as well as unusual components such as, in echinoderms, neurosecretory-like cells that receive motor innervation. The mechanisms underpinning the adaptability of these tissues are not completely understood. Biomechanical changes can lead to an abrupt increase in stiffness (increasing protection against predation) or to the detachment of body parts (in response to a predator or to adverse environmental conditions) that are regenerated. Apart from these advantages, the responsiveness of echinoderm and sponge collagenous tissues to ionic composition and temperature makes them potentially vulnerable to global environmental changes., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Sexual steroids (testosterone and estradiol) were measured in the whole body of wild specimens of the crinoid Antedon mediterranea collected from the Tyrrhenian Sea (Italy). Testosterone levels (274-1,488 pg/g wet weight (w.w.)) were higher than those of estradiol (60-442 pg/g w.w.) and no significant differences between males and females were observed. No clear seasonal trend was either detected - individuals from February, June and October 2004 analyzed - apart from a peak of estradiol in males in autumn. Nonetheless, dramatic changes on tissue steroid levels were observed when individuals were exposed to model androgenic and anti-androgenic compounds for 2 and 4 weeks. The selected compounds were 17 alpha-methyltestosterone (17 alpha-MT), triphenyltin (TPT), fenarimol (FEN), cyproterone acetate (CPA), and p,p'-DDE. Endogenous testosterone levels were significantly increased after exposure to 17 alpha-MT, TPT and FEN, while different responses were observed for estradiol; 17 alpha-MT and FEN increased endogenous estradiol (up to seven-fold), and TPT lead to a significant decrease. Concerning the anti-androgenic compounds, CPA significantly reduced testosterone in a dose-dependent manner without altering estradiol levels, whereas specimens exposed to p,p'-DDE at a low dose (24 ng/L) for 4 weeks showed a four-fold increase in T levels. Overall, the data show the ability of the selected compounds to alter endogenous steroid concentrations in A. mediterranea, and suggest the existence in this echinoderm species of vertebrate-like mechanisms that can be affected by exposure to androgenic and anti-androgenic chemicals.