FISHERY BULLETIN: VOL. 11. NO. 1 



one control crab were utilized for each compound. 

 No feeding responses were observed in any of 

 the test crabs while all of the controls were 

 positive. A second series of bioassays was 

 designed to determine the onset of inhibition. 

 The crabs were placed in seawater and stimu- 

 lated with 20 fji\ aliquots of a solution of 3 mM 

 taurine and 1 jliM quinone. The stimulus was 

 administered at 2 sec intervals to alternate 

 antennules. Inhibition of the "feeding response" 

 was observed at approximately 10 sec. The 

 naphthazarin derivatives were apparently more 

 potent than the juglone derivatives. We interpret 

 these results as indicative of a "cryptic odor" 

 function; the crabs cannot detect the feeding 

 stimulant after a brief exposure to the quinone. 



Many higher plants contain juglone or other 

 hydroxynaphthoquinones or benzoquinones. 

 These compounds also occur in fungi, lichens, 

 pholangids, millipedes, and insects. 1,4-benzo- 

 quinones are the most common ingredient of 

 insect defensive secretions and the 2,5-sub- 

 stituted 1,4-benzoquinones are characteristic of 

 fungi. A similar "cryptic odor" function may be 

 predicted for these compounds. 



Norris (1969) compared the feeding deterrent 

 activity of a number of substituted naphthoquin- 

 ones. Juglone (1) and naphthazarin (2) were the 

 most potent inhibitors. The apparent effective- 

 ness of the hydroxy groups in the 5- or 5,8- 

 positions in these naphthoquinones suggests an 

 examination of the function of the major group 

 of secondary plant metabolites, the flavones 

 (5) (Harborne, 1972) which have a marked 

 structural similarity. 



Whittaker and Feeny (1971) predict "that 

 research into the relations of multicellular 

 marine algae and their consumers will reveal 

 chemical defenses and responses paralleling 

 those of higher plants and animals on land." 

 The most likely candidates to fulfill this predic- 

 tion are the highly halogenated hydrocarbons 

 that are synthesized by algae and stored in the 

 tissues of the herbivorous gastropod, Aplysia 

 caHfornica (Faulkner and Stallard, 1973; 

 Faulkner et al., 1973). We would add to the 

 prediction of Whittaker and Feeny that research- 

 into the relations of many marine inverte- 

 brates and their predators may reveal allomones. 

 Some of the "natural products" of marine 

 invertebrates that have been recently character- 

 ized and that may have this function are the 

 halogenated antibiotics that have been isolated 



from, sponges (Sharma, Vig, and Burkholder, 

 1970; Fattorusso, Minale, and Sodano, 1972; 

 Moody et al., 1972; Anderson and Faulkner, 

 1973). Steroid saponins that are toxicants or 

 irritants have been characterized from holo- 

 thuroids and starfish (Yasumoto, Nakamura, 

 and Hashimoto. 1967; Tursch et al., 1967; 

 Roller et al., 1969; Tursch, Cloetens, and 

 Djerassi, 1970; Turner, Smith, and Mackie, 

 1971). 



We recall a simple demonstration by the 

 late C. F. A. Pantin of the sensitive chemo- 

 sensory capability of sea anemones for saponin. 

 The nematocysts of sea anemones require 

 both a mechanical and a chemical stimulus for 

 discharge. One can brush the surface of a sea 

 anemone's tentacles with a clean glass rod 

 without effecting any discharges. If, however 

 the glass rod is first dipped into a dilute saponin 

 solution, a massive discharge is effected. 



An observation by Clark (1921) suggests 

 the existence of allomones in crinoids. He 

 discusses the avoidance of comatulid crinoids 

 by fish and suggests the activity of glands at the 

 base of the tentacles. The comatulids are 

 unique in containing both polyhydroxyanthro- 

 quinones and aromatic polyketides (Kent, Smith, 

 and Sutherland, 1970; Smith and Sutherland, 

 1971). 



MARINE KAIROMONES 



As in the terrestrial environment, in- 

 vertebrates utilize chemical cues to locate hosts 

 or to warn of predators. Davenport (1966) 

 demonstrated the response of commensal poly- 

 noid polychaetes to a "host factor" in the water 

 draining from tanks containing the host species 

 of starfish. In an electrophysiological analysis 

 of the antennular chemoreceptors of two com- 

 mensal shrimps. Ache and Case (1969) demon- 

 strated the specificity of the response to "host 

 water" from the specific hosts, Haliotis spp. 

 and Stro)igyloceiitrotus spp. 



Predatory starfish induce an escape response 

 in a variety of molluscs (Feder, 1967), and 

 these behavioral responses probably effectively 

 reduce the predation on these species that can 

 detect the predator (Feder, 1963). The active 

 materials in extracts of the starfish Marthasteria 

 glaciali.s and Asten'a.s nibcHs which induce the 

 escape response have been shown to be steroid 

 saponins (Mackie, Lasker, and Grant, 1968). 



