Table 1.

Summarized χ² goodness-of-fit test results for olfactory choice trials using two species of coral-dwelling crab; the Pocillopora-obligate Trapezia cymodoce, and the Acropora-obligate Tetralia glaberrima. Trials are as indicated in figure 4 and electronic supplementary material, figure S1, using the odours of Pocillopora damicornis (magenta), Acropora spathulata (green), filefish fed P. damicornis (orange), and filefish fed A. spathulata (blue). Where significant χ²-values were identified, standardized residuals (sr) identified variables selected more or less than expected by chance, with key variables indicated in the ‘driven by’ column. If crabs were associated with the central habitat patch more or less than expected under the null hypothesis, this is indicated as ‘no choice’. Crabs per trial, n = 16.

	trial	χ2 (d.f.)	p-value	driven by	sr
T. cymodoce		16.63 (2)	<0.01	coral P	3.22
		9.88 (2)	<0.01	fish P	2.46
		1.63 (2)	>0.05	—	—
		1.63 (2)	>0.05	—	—
		4.63 (2)	>0.05	—	—
		6.5 (2)	0.04	fish P	2.02
		12.88 (2)	<0.01	coral P	2.89
T. glaberrima		21.73 (2)	<0.01	coral A	3.76
		9.13 (2)	0.01	fish A	2.46
		3.5 (2)	>0.05		—
		0.13 (2)	>0.05		—
		9.5 (2)	<0.01	coral A	2.02
				no choice	−2.31
		6.13 (2)	0.04	coral A	2.02
		7.63 (92)	0.02	fish A	2.02