And to top it off, it includes a
TailFan design, which spaces arrows properly so fletchings don't touch, and hosts a string facing arrow gripper for quick arrow loading and nocking.
The crayfish hindgut is a muscular tube that extends from mid-thorax to the anus in the
tailfan (Fig.
Crayfish, Cherax destructor, of 6-10 cm rostrum to
tailfan, were obtained from a commercial supplier and maintained in fiberglass aquaria (120 X 50 X 20 cm) at 18 [degrees]C [+ or -] 1 [degrees]C and an artificial 12 h/12 h light/dark cycle.
The functional outcome is flexibility of position and movement at the other end of the tail where the biramous appendages (uropods) of the sixth abdominal segment, together with the telson, form a
tailfan (Fig.
Although both structure and function of crustacean statocysts are well understood, their growth has not been described as it has for other cuticular sensors on the crayfish and lobster tailfan (Letourneau, 1976; Schmitz, 1992; Stuart and Macmillan, 1997) and other appendages (Sandeman and Sandeman, 1996; Macmillan et al., 1998; Steullet et al., 2000).
Post embryonic development of the crayfish Procambarus clarkii and its tailfan mechanosensory system.
4) would seem to allow stage III animals to generate more thrust during a tailflick, and the increase in abdominal size (and therefore muscle mass) would presumably allow these animals to generate the force required to drive the proportionally larger tailfan. Stage IV postlarvae have larger tailfans than stage III larvae (Fig.
Phillips and Olsen (1975) described a similar behavior in response to a touch stimulus by the pelagic puerulus larva of the Western rock lobster (Panulirus longipes) in which the animal "spreads its antennae to an angle of approximately 60[degrees] and the legs, abdomen and tailfan are also extended, while the animal remains motionless." Zoea larvae of the estuarine crab Rhithropanopeus harrisii also flare their antennal spines and flex their abdomens back over their carapace in response to a threatening stimulus (Morgan, 1987).
Directionality of antennal sweeps elicited by water jet stimulation of the tailfan in the crayfish Procambarus clarkii.
The tailfan angle with respect to the abdomen in the snapper (0 [degrees] - fully folded, 90 [degrees] - bent downwards, 180 [degrees] - stretched out) during the snap.
Regardless of the condition of the snapper claw, frontal appendages (antennae, snapper claw, and pincer claw) were most frequently used in tactile interactions before snapping, while carapace, tailfan, and legs (summarized as B for "body") were less often contacted [ILLUSTRATION FOR FIGURE 2A, B OMITTED].
The tailfan is usually kept at about a fight angle downward from the abdomen (circular mean for intact snappers: 73.6 [degrees] [+ or -] 35.8 [degrees], n = 205, r = 0.805; circular mean for deprived snappers: 89.0 [degrees] [+ or -] 41.0 [degrees], n = 26, r = 0.750), which simultaneously stabilizes the stance of the snapping animal and prepares it for escape after the snap (see below).