Radiata2010(4)e

Dieter Gramentz Fig. 3.

Dieter Gramentz Fig. 3. Adult Apalone ferox with the mouth open, trying to scare off a mammal dummy predator in the shape of a teddy bear. As is illustrated in Figs. 1A and B, touching the carapace on the side will lead to the shell being lifted on the opposite side to about half of its length. To this end, the limbs on the opposite side of the stimulus will be stretched to full length. The hind leg on the side of the stimulus will be retracted under the shell, and the front leg will be stretched only a little, with the claws being anchored in the ground. Figure 1C shows the response to the dummy approaching from the front and above. The rear margin of the shell is lifted up and forward by stretching the hind legs. The head is retracted to the level of the eyes, and the front legs are also retracted to the largest extent. The anterior portion of the plastron touches the ground. Figures 1D-F show the sequence of a forward-leap triggered by a touch from the beak dummy. The body is propelled forward by a powerful push with the hind legs. The hind legs are fully stretched, with the claws finding purchase in the ground. Figure 1D shows that the anterior portion of the plastron and the front legs are about 4-6 cm above the ground. The mouth is slightly open and the head retracted to the level of the eyes. The rear margin of the carapace is slightly bent upwards. Figure 1E illustrates that while the positions of shell, limbs and head have remained the same as in Fig. 1D, the anterior margin of the plastron has by now been propelled by the powerful push to about 10-12 cm above the ground. In Fig. 1F, the turtle has assumed an almost upright position in the leap even though its fully stretched hind legs maintain a minimum of contact with the ground. The head is fully retracted into the shell. Figure 1G shows a forward leap from the head-on perspective of a frontally approaching “predator” (human on all fours). Fig. 4A-L: Stills from a film of the same Apalone ferox male leaping and landing upside down (explained 28 RADIATA 19 (4), 2010

Florida Soft-shelled Turtle, Apalone ferox The mouth is open in this instance. Only the claws of the hind legs keep contact with the ground and so prevent the turtle from slipping during the leap forward. The position of the body above the ground about corresponds to that in Fig. 1E. The turtle in Fig. 1H was lifted and held on the rear margin of its shell. All limbs are retracted into the shell and so is the head except for the anteriormost portion of the long nose. All three turtles responded to a lateral touch with lifting the carapace obliquely against the direction of the contact. This lateral lifting of the shell towards the beak dummy was achieved mainly by stretching the front leg of the opposite side. If the anterior area of the carapace is touched, the response may either be a lifting of the posterior portion of the carapace up to a height of appr. 5 cm above the ground by stretching the hind legs (female 1, comp. Tab. 1), or a leap towards the “attacker”. The closer the touch is to the centre of the shell, the more likely the lifting of the rear portion of the shell is. On the other hand, the closer the touch of the beak dummy lies to the anterior margin of the carapace, the head or the front legs of the turtle, the more likely a leap towards the dummy becomes. If the beak dummy approaches head on, the plastron will be lifted off the ground on spread front legs to about 3 cm in the front and about 2 cm in the rear (female 1). The body position is always maintained over just a few seconds. The turtles may spend the time between touches by the dummy beak resting passively on the plastron and scanning the surroundings, or walking off at a moderate pace; the walking speed over a distance of 2 m was 9.5-11.5 seconds (male 1). When passively resting on the plastron, the head will only be retracted to a point at which the eyes are free to scan the surroundings. The front legs may be fully retracted temporarily, but are mostly kept thus that the claws extend just over the margin of the plastron and touch the ground. The hind legs are more or less concealed under the rear margin of the carapace. When lifted off the ground and held, female 1 would discharge a foul-smelling, slightly yellowish fluid first from one and then from both inguinal glands, depending on the intensity of the handling. This species’ most impressive expressions of the behavioural repertoire displayed in self-defence certainly are its forward leaps. Such a leap may be anticipated if a turtle is approached to a distance of less than one metre. These leaps did not serve to increase the distance, i.e., flight, but were always aimed at the predator. Every dummy is attacked thus with the mouth slightly open, but merely butted with the head and shell and not bitten. A leap may occasionally also be launched from the position of a posteriorly raised shell. Leaps may furthermore be executed as individual events, at intervals with walking in between, in series of leaps without intervals, or with intervals of several seconds as individual responses to individual stimuli. in the text). RADIATA 19 (4), 2010 29