# Starfish (DD-122)

> Sea stars, often called starfish, are echinoderms, related to sea urchins and sand dollars, not fish. Many can regrow lost arms, a process that can take months to a year or more. Because most of their vital organs extend into the arms, some species can regenerate a whole new animal from a single severed arm, as long as it keeps part of the central disc; a few, such as some Linckia species, can do it from an arm alone. Some also reproduce asexually by splitting. The footage shows sea stars on the seabed and close-ups of their tube feet.

- Department: Nature
- First published: 2023-12-14
- Last updated: 2023-12-14
- Permalink: https://detailenjoyer.com/case/starfish/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-122-F01**: Sea stars are echinoderms, not fish. _(Write-up · Exhibit A (Not fish))_
- **DD-122-F02**: Many sea stars can regrow lost arms. _(Write-up · Exhibit B (Regrowing arms))_

## Write-up

A sea star can regrow a lost arm. In some species, a severed arm can grow a whole new body.

1. **Not fish**: Sea stars are echinoderms, related to sea urchins.
2. **Regrowing arms**: Many sea stars can regrow lost arms.
3. **It takes time**: Regrowth can take months to a year or more.
4. **A whole new animal**: Some species can regrow a whole body from an arm with part of the disc.
5. **Splitting**: Some sea stars reproduce asexually by splitting.

## Related case files

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

## Reel vs. record

- **Note**: 'A severed arm can even regenerate an entirely new starfish': right for some species; most need part of the central disc attached.

## Video: Starfish: A Sea Star Can Regrow a Lost Arm

- Duration: 17.6 s · Published: 2023-12-14
- File: https://detailenjoyer.com/assets/videos/C03GheQu5qG.mp4

### Transcript

Starfish also known as sea stars are remarkable creatures capable of regenerating lost body parts. DID YOU KNOW? If starfish loses an arm it can often grow a new one. In some cases a severed arm can even regenerate an entirely new starfish, making them exceptional in the realm of regenerative abilities in the animal kingdom. NOW YOU KNOW!

## Questions & answers

**Q: What group are sea stars in?**  
A: They're related to sea urchins. _(Source: Write-up · Exhibit A (Not fish) · NOAA Ocean Service: Is a starfish a fish?)_

**Q: What can many sea stars regrow?**  
A: It's a slow process. _(Source: Write-up · Exhibit B (Regrowing arms) · NOAA Ocean Service: Is a starfish a fish?; Wikipedia: Starfish)_

**Q: How long can regrowth take?**  
A: It depends on the species. _(Source: Write-up · Exhibit C (It takes time) · Wikipedia: Starfish)_

**Q: What does an arm usually need to grow a new body?**  
A: A few species manage without it. _(Source: Write-up · Exhibit D (A whole new animal) · NOAA Ocean Service: Is a starfish a fish?; Wikipedia: Starfish)_

**Q: How else can some sea stars reproduce?**  
A: That's asexual reproduction. _(Source: Write-up · Exhibit E (Splitting) · Wikipedia: Starfish)_

## Sources

- [NOAA Ocean Service: Is a starfish a fish?](https://oceanservice.noaa.gov/facts/starfish.html)
- [Wikipedia: Starfish](https://en.wikipedia.org/wiki/Starfish)

## Cite this case file

Easterling, Marcus. "Starfish." The Detail Department (DetailEnjoyer), case file DD-122, last updated Dec 14, 2023. https://detailenjoyer.com/case/starfish/