# Blue Bloods (DD-193)

> Squid, like octopuses and cuttlefish, have three hearts: two branchial hearts pump blood through the gills, and a systemic heart pumps it around the body. Their blood is blue when oxygenated because it uses hemocyanin, a copper-containing protein, to carry oxygen, instead of the iron-based hemoglobin in human red blood cells. Hemocyanin is dissolved in the blood rather than packed into cells. The footage shows squid swimming, with the presenter.

- Department: Nature (also Science)
- First published: 2024-01-21
- Last updated: 2024-01-21
- Permalink: https://detailenjoyer.com/case/blue-bloods/
- Original Reel title: Blue Bloods 🦑
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-193-F01**: Squid have three hearts. _(Write-up · Exhibit A (Three hearts))_
- **DD-193-F02**: Two hearts pump blood to the gills. _(Write-up · Exhibit B (Gill hearts))_

## Write-up

Squid have three hearts and blue blood. Copper-based hemocyanin carries their oxygen.

1. **Three hearts**: Squid have three hearts.
2. **Gill hearts**: Two hearts pump blood to the gills.
3. **Systemic heart**: One heart supplies the body.
4. **Hemocyanin**: Copper-based hemocyanin carries oxygen.
5. **Blue color**: Oxygenated hemocyanin is blue.

## Related case files

- [Jellies (DD-143)](https://detailenjoyer.com/case/jellies/): I linked more sea creatures
- [Seahorse Secrets (DD-191)](https://detailenjoyer.com/case/seahorse-secrets/): I linked more odd ocean biology

## Reel vs. record

- **Note**: None needed.

## Video: Blue Bloods: Squid Have Three Hearts and Blue Blood

- Duration: 17.2 s · Published: 2024-01-21
- File: https://detailenjoyer.com/assets/videos/C2WcubNNzyo.mp4

### Transcript

Squid have three hearts and blue blood. Two of the hearts pump blood to the gills, while the third pumps it to the rest of the body. DID YOU KNOW? The blue color of their blood comes from a copper-based molecule called hemocyanin, which is used to transport oxygen. This is different from humans, whose blood is iron-based and red when oxygenated. NOW YOU KNOW!

## Questions & answers

**Q: How many hearts does a squid have?**  
A: Like octopuses. _(Source: Write-up · Exhibit A (Three hearts) · Wikipedia: Squid)_

**Q: What do two of them pump to?**  
A: Branchial hearts. _(Source: Write-up · Exhibit B (Gill hearts) · Wikipedia: Squid)_

**Q: What carries oxygen in squid blood?**  
A: Copper-based. _(Source: Write-up · Exhibit C (Systemic heart) · Wikipedia: Squid)_

**Q: What color is it when oxygenated?**  
A: Hence the title. _(Source: Write-up · Exhibit D (Hemocyanin) · Wikipedia: Hemocyanin)_

**Q: Which metal is in human hemoglobin?**  
A: Red blood. _(Source: Write-up · Exhibit E (Blue color) · Wikipedia: Hemocyanin)_

## Sources

- [Wikipedia: Squid](https://en.wikipedia.org/wiki/Squid)
- [Wikipedia: Hemocyanin](https://en.wikipedia.org/wiki/Hemocyanin)

## Cite this case file

Easterling, Marcus. "Blue Bloods." The Detail Department (DetailEnjoyer), case file DD-193, last updated Jan 21, 2024. https://detailenjoyer.com/case/blue-bloods/