Nonmammalian Spermatozoa

The sperm chemoattractants in nonmammalian species vary to a large extent. Some examples are shown in Table 2. So far, most sperm chemoattractants that have been identified in animals are peptides or low-molecular-weight proteins (l-20kDa), which are heat stable and sensitive to proteases [35, 102]. Exceptions to the rule are the sperm chemoattractants of corals—lipid-hke substances of 140-250 Da [30], and the chemoattractants of the ascidians Ciona—a sulfated steroid [187, 189]. In plants such as ferns, the partially ionized form of malic acid and a large variety of unsaturated four-carbon cis-dicarbojg lic acids are sperm chemoattractants [35], In algae, low-molecular-weight 

Pheromones are substances secreted by an individual and sensed by a second individual of the same species, in which they trigger a specific action. 

Algae Low-molecular-weight unsaturated pheromones of cyclic or linear structure (for example 532 Da pentosylated hydroquinone in the case of Chlamydomonas allensworthii) [35, 92, 155] 

Ascidians SAAF—a sulfated steroid 3, 4, 7, 26-tetrahydroxycholestane-3, 26-disulfate (for dona savignyi and intestinalis) [187-189] 

Corals A lipid-like long chain fatty alcohol CH3-(CH2)8-CH=CH-CH=CH-CH20H (for Montipora digitata) [30] 

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