Metrius contractus on a leaf feeding. Image taken by and used with permission from Sarah Crews.

Explanation of Terms

Anterior - the end of a bilaterally symmetrical animal's body containing its head (Pearson 2007)

Aqueous- a kind of solution that contains water as a solvent (Eisner et al. 2000, Campbell et al. 2008)

Bacteria -one of two prokaryotic domains of life (Campbell et al. 2008)

Chitin- structural support material found in arthropods; considered to be a polysaccharide (Campbell et al. 2008). 

Clades- a group of species with a common ancestor and all of its descendents (Campbell et al. 2008)

Conjugated dienes- a carbon chain containing two double bonds on carbons that are separated by one single bond; this conjugation greatly increases the stability of molecules (Carey and Giuliano 2013)

Convergent evolution- occurs when species evolve correlative features in separate lineages (Campbell et al. 2008)

Cuticle - the outer layer, or exoskeleton, of the arthropod; consists of chitin and protein (Campbell et al. 2008)

Cytoskeleton- network of fibers involved in the support of the cell (Lodish et al. 2013)

Ecdysis - the shedding or molting of the outer chitinous layer of an arthropod to allow for growth; all athropods undergo this process (Campbell et al. 2008) 

Efferent duct - a duct that functions to move fluid away from a concentrated center (Pearson 2007)

Endosymbiosis- an organism, commonly called the host cell, takes in another cell and they live together functionally; the newly incorporated cell often becomes an organelle in the host cell; ie. mitochondria and chloroplasts (Campbell et al. 2008). 

Enthalpy- the amount of energy contained within a molecule; often expressed as an overall change in total internal energy for a reaction (Campbell et al. 2008)

Enzymes - special proteins that catalyze chemical reactions by lowering activation energy but are never consumed by the reaction (Pearson 2007); allow for a very fast reaction in the jets of the bombardier beetle (Eisner et al. 2000)

Exoskeleton - supportive and protective hard skeleton on the outside of an animal's body; serves as place for muscles to attach; found in mollusks and arthropods (Campbell et al. 2008)

Exothermic- a reaction that emits heat after completion; has a negative change in enthalpy value (Carey and Giuliano 2013); reactions in bombardier beetle jets release very hot chemicals due to being very exothermic (Beheshti and McIntosh 2007)

Gland - specialized structure equipped with modified epithelial tissue for the production and secretion of a compound (Pearson 2007)

Homologous traits- traits that are similar because of a common ancestor (Campbell et al. 2008)

Hydrocarbon- a molecule containing only hydrogen and carbon (Carey and Giuliano 2013); very hydrophobic in nature which affects reactivity (Campbell et al. 2008)

Organelles- specialized compartments in a cell that are responsible for certain functions; can be found in the cytosol of eukaryotic cells (Campbell et al. 2008)

Oxidation - a powerful reaction always accompanied by reduction in redox reactions; electrons are lost by the reactant experiencing oxidation and gained by the reactant being reduced (Pearson 2007)

Peroxide- compound with two oxygens bonded to each other and another group (Carey and Giuliano 2013); reactant heavily involved in oxidation reactions in the jets of bombardier beetles (Schwarcz 2010)

Posterior - the rear end of a bilaterally symmetrical animal's body (Pearson 2007)

Quinone - a product of the oxidation of derivatives of benzene rings resulting in a conjugated diene with two double bonded oxygens and sometimes other substituents which are indicated by a prefix (Carey and Giuliano 2013); irritating chemical found in all bombardier beetles (Beheshti and McIntosh 2007)

Reaction Chamber - compartment where reactants are combined to form the toxic spray of the bombardier beetle; made with thick, rigid walls to protect the body of the beetle from the potent oxidation reaction that occurs inside (Eisner et al. 2000)

Stereochemistry- the variation in the ways atoms are arranged spatially around a molecule impact its reactivity and properties (Carey and Giuliano 2013)

Storage Chamber - also referred to as the reservoir; compartment that stores hydroquinones and peroxides for later reaction in bombardier beetles (Beheshti and McIntosh 2007); made with relatively thin flexible walls protected by a cuticle layer (Eisner et al. 2000)

Temperate grasslands- a type of geographical habitat found primarily in North America and Russia (Campbell et al. 2008)

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