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Snap traps

Snap traps use electricity and hydraulics to prepare and launch their attack

The snap trap is the most well-known trapping mechanism of carnivorous plants. Ingeniously, snap traps use electricity and hydraulics to prepare and launch their attack. Inside the plant, electric pulses track and remember prey movements. With perfect timing, a quick shift of water (hydraulics) within the trap walls causes them to bend and snap!

    Sequence of a Venus fly trap snap trap in action

    1. Tender Trap - Open traps are velvety red and smell sweetly of nectar, confusing unwary prey. Mistaking a trap for a flower, they enter the gaping maw.

    2. One…Two…too late - Touching a trigger hair, they put the plant on high alert. A second touch within 20 seconds … and the jaws snap closed in a lethal bite.

    3. Air-tight Tomb - At first the trap is ajar, and small animals escape. The large, juicy prey are caught: They struggle, the trap seals tight, and digestion begins.

Plants with bite – snap traps

Trick – open Venus fly trap © G Bourke

Trap – partially closed Venus fly trap

Sealed tight – Venus fly trap (Dionaea muscipula) with march fly prey Greg Bourke

Venus flytrap (Dionaea muscipula) growing in The Calyx, Royal Botanic Gardens, Sydney Image - Caroline Seltz

Waterwheel (Aldrovanda vesiculosa) in cultivation. © G Bourke

Waterwheel habitat near Armidale, New South Wales © G Bourke

Activities - Snap traps 

1. Identifying structural adaptations

Identify and list the structural adaptations of the Venus fly trap that enable it to entice and trap prey. 

2. Observing

Observe the structural adaptations of the plant. Draw and label a scientific diagram of its snap trap. Label the functions and mechanics of its features.

3. Re-enact

Use puppets and props, such as gloved hands, to create an enactment or video that describes the plant’s adaptations and explains the trapping steps and mechanisms. 

4. Caring for a Venus Fly Trap

Keep a Venus fly-trap in the classroom. Refer to How to care for a Venus fly trap 

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