Gymnarchus

Gymnarchus niloticus – the aba, aba aba or frankfish – is an electric fish, living at the bottoms of rivers and lakes. It is the only species in the genus Gymnarchus and the family Gymnarchidae, within the order Osteoglossiformes. It is a long slender fish with no pelvic or anal fins, and a tail fin shaped like a rat's tail. It swims using its elongated dorsal fin, allowing it to keep its body straight while it moves. This in turn enables it to produce a steady but weak electric field, which it uses to locate its prey. It is large for a river fish; adults can reach 1.6 m (5.2 ft) in length and 19 kg (42 lb) in weight.

Gymnarchus

Wiki-Harfus ; modified by Wildfeuer · 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
aba knifefishPBDB
Sits inside
GymnarchidaePBDB
Diet
carnivorePBDB, for Osteoglossiformes
Life habit
nektonicPBDB, for Osteoglossiformes
Motility
actively mobilePBDB, for Osteoglossiformes
Environment
freshwaterPBDB, for Osteoglossiformes

Time the record covers

At least 33 million years on record.

The record covers at least 33.9 Mya to 11.7 ka. No occurrence read is dated outside 48.07 Mya to 0 Mya.

Eocene — about 3 of 42 occurrencesEoceneOligocene — about 1 of 42 occurrencesOligoceneMiocene — about 13 of 42 occurrencesMiocenePliocene — about 10 of 42 occurrencesPleistocene — about 13 of 42 occurrences49–47 Mya — about 0.1 occurrences47–46 Mya — about 0.3 occurrences46–44 Mya — about 0.3 occurrences44–42 Mya — about 0.3 occurrences42–41 Mya — about 0.3 occurrences41–39 Mya — about 0.3 occurrences39–38 Mya — about 0.3 occurrences38–36 Mya — about 0.3 occurrences36–34 Mya — about 0.3 occurrences34–33 Mya — about 0.1 occurrences28–26 Mya — about 0.3 occurrences26–25 Mya — about 0.4 occurrences25–23 Mya — about 0.4 occurrences23–21 Mya — about 0.6 occurrences21–20 Mya — about 0.8 occurrences20–18 Mya — about 1 occurrence18–16 Mya — about 1 occurrence16–15 Mya — about 0.7 occurrences15–13 Mya — about 0.6 occurrences13–11 Mya — about 0.8 occurrences11–9.8 Mya — about 2 occurrences9.8–8.2 Mya — about 2 occurrences8.2–6.5 Mya — about 2 occurrences6.5–4.9 Mya — about 4 occurrences4.9–3.3 Mya — about 6 occurrences3.3–1.6 Mya — about 12 occurrences1.6–0 Mya — about 5 occurrences33.9 Mya11.7 ka49 Mya0 Mya

42 occurrences of Gymnarchus on record, most of them in the Pleistocene. The Paleobiology Database records this as a living group. 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

42 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

12 formations

Koobi Fora — 3.78°N, 36.33°EKoobi Fora — 3.59°N, 36.24°EKoobi Fora — 3.90°N, 36.24°EKoobi Fora — 4.07°N, 36.37°EKoobi Fora — 3.89°N, 36.29°EKoobi Fora — 3.75°N, 36.36°EKoobi Fora — 4.06°N, 36.33°EKoobi Fora — 3.91°N, 36.38°EKoobi Fora — 4.15°N, 36.40°ENkondo — 1.50°N, 31.00°ENachukui — 2.90°N, 36.05°ENyaburogo — 1.00°N, 30.50°EShungura — 5.08°N, 36.03°EKakara — 1.00°N, 30.50°ELusso Beds — 0.03°N, 29.62°ENawata — 2.90°N, 36.05°ENawata or Nachukui — 2.90°N, 36.05°EWarwire — 1.50°N, 31.00°ELokone Sandstone — 2.22°N, 35.57°EMaradah — 28.58°N, 19.90°E

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The named rock units Gymnarchus has been recovered from, largest first. Drawn where the rock is now, not where it formed. 6 occurrences have no formation on record, which is common for older literature.

Gymnarchus and its relatives

Pleistocene

Where Gymnarchus and its relatives were recorded in the Pleistocene.

Found in the same rock

424 taxa

The Paleobiology Database records 42 sites for Gymnarchus, 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

24 references

Each of the 42 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. 12 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 content2

Picture of Gymnarchus

Credit
Wiki-Harfus ; modified by Wildfeuer
Licence
CC BY-SA 3.0
Commercial use
the licence allows it

CT scan

Licence
not stated by the source
Commercial use
cannot be read from the licence given — check the record
Specimen
Gymnarchus niloticus · CUMV:Fish:80334

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 itGymnarchidae through timeFormations of the PleistoceneThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Cuvier 1829