Chaetognatha

The Chaetognatha or chaetognaths are a phylum of predatory marine worms that are a major component of plankton worldwide. Commonly known as arrow worms, they are mostly pelagic; however about 20% of the known species are benthic, and can attach to algae and rocks. They are found in all marine waters, from surface tropical waters and shallow tide pools to the deep sea and polar regions. Most chaetognaths are transparent and are torpedo shaped, but some deep-sea species are orange. They range in size from 2 to 120 millimetres.

Chaetognatha

Varios autores. Compilación por mí. · CC BY-SA 3.0 · via Wikipedia/Commons. May be a photograph of a specimen, or an artist’s reconstruction — an interpretation of a skeleton, since colour and soft tissue are almost never preserved.

On record

Recorded, not inferred
Also called
arrow wormPBDB
Sits inside
ChaetognathiferaPBDB
Diet
carnivorePBDB
Life habit
nektonicPBDB
Motility
actively mobilePBDB

Time the record covers

At least 220 million years on record.

The record covers at least 530.7 Mya to 309.8 Mya. No occurrence read is dated outside 538.8 Mya to 307.4 Mya.

Cambrian — about 297 of 300 occurrencesCambrianOrdovician — about 1 of 300 occurrencesOrdovicianSilurian — about 0 of 300 occurrencesDevonian — about 0 of 300 occurrencesCarboniferous — about 2 of 300 occurrencesCarboniferous543–535 Mya — about 31 occurrences535–527 Mya — about 79 occurrences527–519 Mya — about 87 occurrences519–511 Mya — about 46 occurrences511–503 Mya — about 50 occurrences503–495 Mya — about 5 occurrences455–447 Mya — about 0.7 occurrences447–439 Mya — about 0.3 occurrences311–303 Mya — about 2 occurrences530.7 Mya309.8 Mya543 Mya303 Mya

300 occurrences of Chaetognatha on record, most of them in the Cambrian. The Paleobiology Database records this as a living group, and the chart stops with its fossils rather than at the present. Bar height is expected occurrences, not a count: each fossil is spread across the span it is dated to, so a tall narrow bar means tight dating and a low wide one means loose.

When

300 occurrences

These are dates about fossils, not the animal: the record can only begin after it arose and end before it died out, so either end may reach further. Shares are expected occurrences: a fossil dated to a span is counted partly in each period it straddles. More on what this infers.

Found in

52 formations

Dengying — 30.77°N, 111.32°EDengying — 32.50°N, 107.00°EDengying — 32.35°N, 106.83°EDengying — 25.48°N, 103.03°EDengying — 26.63°N, 105.85°EDengying — 28.27°N, 106.30°EDengying — 32.35°N, 106.82°EDengying — 28.27°N, 103.40°EDengying — 30.73°N, 111.13°EDengying — 30.77°N, 111.12°EDengying — 25.52°N, 103.07°EDengying — 24.72°N, 102.56°EKuonamka — 70.74°N, 112.98°EKuonamka — 70.22°N, 113.70°EKuanchuanpu — 33.00°N, 106.17°EKuanchuanpu — 32.50°N, 106.92°EKuanchuanpu — 32.94°N, 107.70°EKuanchuanpu — 32.97°N, 106.25°EYanjiahe — 30.73°N, 111.08°EYanjiahe — 30.73°N, 111.03°EYanjiahe — 30.78°N, 111.35°EShabakty — 43.47°N, 69.87°EShabakty — 43.62°N, 69.73°EShabakty — 43.47°N, 69.97°EShabakty — 43.68°N, 69.68°EShabakty — 43.60°N, 69.45°EMaidiping — 29.53°N, 103.39°ELower Comley — 52.56°N, 2.76°WLower Comley — 52.58°N, 2.67°WLower Comley — 52.54°N, 2.80°WLower Comley — 52.65°N, 2.73°WZhujiaqing — 27.93°N, 103.56°EZhujiaqing — 24.55°N, 102.72°EZhujiaqing — 26.28°N, 103.22°EZhujianqing — 24.73°N, 102.57°EChulaktau — 43.47°N, 69.87°EChulaktau — 43.62°N, 69.73°EChulaktau — 43.37°N, 70.22°EChulaktau — 43.68°N, 69.68°EChulaktau — 43.60°N, 69.45°EKyrshabakty — 43.47°N, 69.87°EKyrshabakty — 43.62°N, 69.73°EKyrshabakty — 43.37°N, 70.22°EKyrshabakty — 43.60°N, 69.45°EBurgess Shale — 51.44°N, 116.47°WManykay — 70.50°N, 103.40°EManykay — 70.67°N, 103.00°EManykay — 70.72°N, 112.76°ETal — 30.35°N, 78.17°ETal — 30.45°N, 78.08°EUst-Yudoma — 57.67°N, 131.83°EUst-Yudoma — 57.17°N, 132.00°EYuanshan — 24.81°N, 102.58°EYuanshan — 24.84°N, 102.41°EHetang — 28.74°N, 118.62°EHuangshandong — 30.83°N, 111.17°EHuangshandong — 30.77°N, 111.13°EBrigus — 45.77°N, 60.29°WHartshill — 52.57°N, 1.55°WChapel Island — 47.00°N, 56.00°WYangjiaping — 29.22°N, 110.85°EBayan Gol — 46.70°N, 96.30°EHuaqiao — 28.39°N, 109.53°E

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The named rock units Chaetognatha has been recovered from, largest first. Drawn where the rock is now, not where it formed. 28 further formations hold fewer occurrences each and are not listed.

Chaetognatha and its relatives

Cambrian

Where Chaetognatha and its relatives were recorded in the Cambrian.

Found in the same rock

937 taxa

The Paleobiology Database records 169 sites for Chaetognatha, and this reads all of them. The number is how many of those sites it was catalogued from too. The 24 sharing the most are listed.

This is not a list of everything alive at the time. It is only what has come out of the same ground as this animal and been written down.

Entered from

62 references

Each of the 300 occurrences read was entered from one of these publications, ordered by how many each accounts for. This is not a search for papers mentioning the name. 50 further references are not listed. Entries link to doi.org where the Paleobiology Database holds an identifier, and to its own record where it does not. Relayed as the Paleobiology Database holds them, not checked against what they resolve to.

Media and terms

Media content1

Picture of Chaetognatha

Credit
Varios autores. Compilación por mí.
Licence
CC BY-SA 3.0
Commercial use
the licence allows it

No 3D scan of Chaetognatha was found in MorphoSource and Sketchfab.

Smithsonian Open Access was not reached for this taxon, so this list is what the others held rather than everything there is.

The description on this site

Licence
CC BY-SA 4.0

This is what the site found, which is not the same as what exists.

Keep going

What may have been alongside itChaetognathifera through timeFormations of the CambrianThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Leuckart 1854