Phylum Chaetognatha: Arrow Worms

The video explores arrow worms, highlighting their unique morphology, predatory behavior, and ecological significance. It delves into their anatomy, including sensory systems and reproductive traits, and discusses their evolutionary history and classification challenges. Arrow worms play a crucial role in the oceanic carbon cycle and have a long evolutionary history dating back to the Cambrian period.

What makes arrow worms morphologically distinct?

• They possess grasping spines for capturing prey.

• They are covered in scales.

• They have a segmented body.

• They have a hard exoskeleton.

Which feature is NOT part of the arrow worm's body structure?

• Cup-shaped eyes

• A segmented tail

• A dorsal brain

• A protective hood

How do arrow worms primarily sense their environment?

• Using echolocation

• By detecting chemical signals

• Through visual cues

• By sensing mechanical vibrations

What is the primary food source for arrow worms?

• Algae

• Copepods

• Plankton

• Small fish

What role do arrow worms play in the oceanic carbon cycle?

• They consume carbon-rich sediments.

• They produce carbon dioxide.

• They release methane.

• They sequester carbon through their migratory patterns.

Where are arrow worms currently placed in the animal phylogenetic tree?

• As a separate phylum

• Within Deuterostomia

• As a sister group to Nematodes

• Within Spiralia

What was a significant challenge in classifying arrow worms?

• Their lack of a nervous system

• Their absence in fossil records

• Their similarity to vertebrates

• Their unique method of development