. The Biological bulletin. Biology; Zoology; Marine biology. PREY CAPTURE IN DEVELOPING SQUID 73 to prey of any type, or in Artemia-reaTed squid exposed to fast-moving copepods for the first time (see below). In addition to outlining the temporal sequence of attack be- havior, the flow chart in Figure 2B also approximates an ontogenic sequence by which the basic attack is perfected after hatching. Refinement in positioning for attack: circling Attacks on both copepods and Artemia nauplii by squid of aU ages studied were attempted from all directions, but the preferred direction of attack chang
. The Biological bulletin. Biology; Zoology; Marine biology. PREY CAPTURE IN DEVELOPING SQUID 73 to prey of any type, or in Artemia-reaTed squid exposed to fast-moving copepods for the first time (see below). In addition to outlining the temporal sequence of attack be- havior, the flow chart in Figure 2B also approximates an ontogenic sequence by which the basic attack is perfected after hatching. Refinement in positioning for attack: circling Attacks on both copepods and Artemia nauplii by squid of aU ages studied were attempted from all directions, but the preferred direction of attack changed over time in the Group 1 squid feeding on copepods. During the earliest feeding trials (days 2-4) most attacks were attempted from the posterior end of the copepod (Fig. 3 A1). Within about one week, however, the frequency of head-on attacks (to- wards the anterior of the copepod) began to increase, and head-on attacks became quite prominent, acounting for about one third of all attempts after day 26 (Figs. 3A2, 3). Successful attacks (open circles in Fig. 3A) appear to be more common with the head-on approach in these older squid. Development of the preference for head-on attacks was not seen in the Group 2, Artemia-kd squid and emerged in Group 1 animals as a variation in the basic attack be- havior that we have labeled "circling" (Fig. 3B). In this case, a squid pursuing a copepod would move angularly, rotating around the copepod, apparently trying to attain a head-on position (1). During this process, the copepod often reacted to the squid's approach by jumping forward at an angle, propelling it out of the squid's line of approach (2). In response, the squid would shift laterally and again approach the copepod, repeating the rotation behavior in another attempt to position itself in front of the copepod (3). This sequence of action and reaction often repeated itself many times, with the pair of animals circling in an expanding spiral (4-9). This interactive beh
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