# Worms This Flat (DD-293)

> Marine polyclad flatworms (Polycladida) are thin, often brightly patterned flatworms found mostly on reefs and rocky shores. They glide on beds of cilia and muscular waves, and most are carnivores that eat small invertebrates such as sea squirts, snails and crustaceans. Some species' bright colors are thought to warn predators that they're distasteful or toxic. The famous experiments where a flatworm is cut into pieces and each regrows into a whole animal mostly involve freshwater planarians, which carry stem cells called neoblasts. The footage shows several colorful marine flatworms rippling over coral and rock.

- Department: Nature
- First published: 2024-08-08
- Last updated: 2024-08-08
- Permalink: https://detailenjoyer.com/case/worms-this-flat/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-293-F01**: Marine polyclad flatworms glide on cilia. _(Write-up · Exhibit A (Polyclads))_
- **DD-293-F02**: Planarians can regrow whole bodies from fragments. _(Write-up · Exhibit E (Planarian regeneration))_

## Write-up

Bright colors can be a warning. Planarians can regrow a whole body from a fragment.

1. **Polyclads**: Marine polyclad flatworms are thin, often colorful reef animals.
2. **Gliding on cilia**: They move on cilia and muscular waves.
3. **Carnivores**: Most eat small invertebrates.
4. **Warning colors**: Some species' bright colors are thought to warn off predators.
5. **Planarian regeneration**: Freshwater planarians can regrow whole bodies from fragments.

## Related case files

- [Bdelloid Rotifers (DD-641)](https://detailenjoyer.com/case/bdelloid-rotifers/): I paired it with another tiny animal with unusual survival tricks

## Reel vs. record

- **Note**: 'If a flatworm is cut in half each piece can grow into a complete organism': I'd attribute this to freshwater planarians, the classic regeneration model, rather than to marine flatworms in general.

## Video: Worms This Flat: Bright Colors Can Be a Warning

- Duration: 27.5 s · Published: 2024-08-08
- File: https://detailenjoyer.com/assets/videos/C-bkWq4pEJj.mp4

### Transcript

DID YOU KNOW? Marine flatworms are fascinating and diverse creatures found in oceans around the world. These vibrant invertebrates come in various colors and patterns which serve as warnings to predators about their toxicity. Flatworms are carnivorous often feeding on small invertebrates and sometimes even each other. They glide gracefully over surfaces using tiny cilia on their undersides. One remarkable feature of marine flatworms is their ability to regenerate. If a flatworm is cut in half each piece can grow into a complete organism. This regenerative ability is a subject of interest in scientific research. NOW YOU KNOW!

## Questions & answers

**Q: What order do marine flatworms in the Reel belong to?**  
A: Polyclads are flatworms. _(Source: Write-up · Exhibit A (Polyclads) · Wikipedia: Polycladida)_

**Q: How do they move?**  
A: They glide over surfaces. _(Source: Write-up · Exhibit B (Gliding on cilia) · Wikipedia: Polycladida)_

**Q: What do most polyclads eat?**  
A: They're carnivores. _(Source: Write-up · Exhibit C (Carnivores) · Wikipedia: Polycladida)_

**Q: What can bright colors signal?**  
A: Some are distasteful or toxic. _(Source: Write-up · Exhibit D (Warning colors) · Wikipedia: Polycladida)_

**Q: Which flatworms are famous for regeneration?**  
A: They carry stem cells called neoblasts. _(Source: Write-up · Exhibit E (Planarian regeneration) · Wikipedia: Planarian)_

## Sources

- [Wikipedia: Polycladida](https://en.wikipedia.org/wiki/Polycladida)
- [Wikipedia: Planarian](https://en.wikipedia.org/wiki/Planarian)

## Cite this case file

Easterling, Marcus. "Worms This Flat." The Detail Department (DetailEnjoyer), case file DD-293, last updated Aug 8, 2024. https://detailenjoyer.com/case/worms-this-flat/