| Feeding by Parasagitta elegans was studied in order to evaluate published hypotheses that chaetognaths use tetrodotoxin to paralyze prey. When feeding on brine shrimp larvae, capture time was 1--5 seconds and swallowing time 10--19 seconds. The sticky oral secretions of chaetognaths were applied to prey and found to immobilize them, but were not toxic. Newly ingested prey, removed from chaetognaths, were immobile and ensheathed in oral secretions. Prey removed within 3 minutes displayed repeated contractions of skeletal muscles for up to 30 minutes. This study reveals that immobilization of prey is due to ensheathment by oral secretions and crushing during ingestion, and not paralysis due to toxins.;To test whether chaetognaths are chemically defended against predation, they were fed to sea anemones (Urticina crassicornis) and tidepool sculpin (Oligocottus maculosus). The predators were not adversely affected by the diet. The role of toxins in arrow worm biology, if any, remains uncertain. |
