Passive and Active Defense in Toads: The Parotoid Macroglands in Rhinella marina and Rhaebo guttatus PEDRO L. MAILHO‐FONTANA 1 , MARTA M. ANTONIAZZI 1 , LUÍS F. TOLEDO 2 , VANESSA K. VERDADE 3 , JULIANA M. SCIANI 1 , KATIA C. BARBARO 1 , DANIEL C. PIMENTA 1 , MIGUEL T. RODRIGUES 4 , AND CARLOS JARED 1 * 1 Instituto Butantan, São Paulo, Brazil 2 Museu de Zoologia, Universidade Estadual de Campinas, Campinas, Brazil 3 Centro de Ciências Naturais e Humanas, Universidade Federal ABC, Santo André, Brazil 4 Departamento de Zoologia, Universidade de São Paulo, São Paulo, Brazil The skin of amphibians is characterized by the presence of mucous glands, mainly associated with protection against desiccation, and granular glands, or poison glands, associated with chemical defense against predators and microorganisms (Toledo and Jared, '95; Hillman et al., 2009). In some species the poison glands are grouped into large and very conspicuous protuberances, such as the parotoid macroglands ABSTRACT Amphibians have many skin poison glands used in passive defense, in which the aggressor causes its own poisoning when biting prey. In some amphibians the skin glands accumulate in certain regions forming macroglands, such as the parotoids of toads. We have discovered that the toad Rhaebo guttatus is able to squirt jets of poison towards the aggressor, contradicting the typical amphibian defense. We studied the R. guttatus chemical defense, comparing it with Rhinella marina,a sympatric species showing typical toad passive defense. We found that only in R. guttatus the parotoid is adhered to the scapula and do not have a calcified dermal layer. In addition, in this species, the plugs obstructing the glandular ducts are more fragile when compared to R. marina. As a consequence, the manual pressure necessary to extract the poison from the parotoid is twice as high in R. marina when compared to that used in R. guttatus. Compared to R. marina, the poison of R. guttatus is less lethal, induces edema and provokes nociception four times more intense. We concluded that the ability of R. guttatus to voluntary squirt poison is directly related to its stereotyped defensive behavior, together with the peculiar morphological characteristics of its parotoids. Since R. guttatus poison is practically not lethal, it is possibly directed to predators' learning, causing disturbing effects such as pain and edema. The unique mechanism of defense of R. guttatus may mistakenly justify the popular myth that toads, in general, squirt poison into people's eyes. J. Exp. Zool. 9999A: XX–XX, 2013. © 2013 Wiley Periodicals, Inc. How to cite this article: Mailho‐Fontana PL, Antoniazzi MM, Toledo LF, Verdade VK, Sciani JM, Barbaro KC, Pimenta DC, Rodrigues MT, Jared C. 2013. Passive and active defense in toads: The parotoid macroglands in Rhinella marina and Rhaebo guttatus. J. Exp. Zool. 9999:1–13. J. Exp. Zool. 9999A:1–13, 2013 Grant sponsor: CAPES and CNPq‐INCTTox—Brazilian Federal Government.  Correspondence to: Carlos Jared, Cell Biology Laboratory, Instituto Butantan, Av. Vital Brasil 1500, CEP 05503‐000 São Paulo, Brazil. E‐mail: jared@butantan.gov.br Received 8 July 2013; Revised 6 September 2013; Accepted 13 September 2013 DOI: 10.1002/jez.1838 Published online XX Month Year in Wiley Online Library (wileyonlinelibrary.com). RESEARCH ARTICLE © 2013 WILEY PERIODICALS, INC.