Fig. 5. Defensive fluid emission mechanism of A. aculeatus. (A) Ventral view; oral effluent (red) has been routed by way of the clefts between the coxae of legs 1 and 2 to the margins of the body. (B) Right-side view; the fluid is seen emerging from between legs 1 and 2 and flowing past the gland opening onto the carapace channel. (C) Quinonoid secretion (blue) has been ejected from the gland opening into the stream of oral effluent. (D) The mixture of oral effluent and secretion has accumulated on the carapace channel.