Color: Whitish or grey when preserved. Pinkish to green in vivo.

Ubiquitous, often found in other invertebrate shells or carapaces. Deposit feeder.

Galapagos Spreading Center, East Pacific Rise, Guaymas Basin, North East Pacific, Lau Back-Arc Basin, North Fiji Back-Arc Basin, Manus Back-Arc Basin, Okinawa Trough, Mariana Back-Arc Basin. Likely a group of cryptic species (see CHEVALDONNÉ et al. 2002).

Ampharetinae with four pairs of smooth gills, no pallae, first three chaetigerous segments reduced, uncini from fourth chaetigerous segment continuing posteriorly on 14 thoracic segments. Uncini avicular with one row of teeth. Buccal tentacles smooth, inserted on a ?buccal membrane?, 12-15 abdominal segment. Tube mucus-lined covered with small chips of volcanic glass or mud.

Maximum size in Guaymas individuals 18 mm, smaller elsewhere.

Size (left): 280µm   Size (right):  435µm

Smallest individuals (3-4 chaetigers) have neither appendages nor distinctive morphology, as shown above left. At around 400µm and 5-6 chaetigers they develop a pair of smooth gills behind the prostomium; the adults will ultimately have four pairs, but the remaining three pairs appear much later in development. Since the smallest larvae are so featureless, it is possible that there may be more than one species represented.

Paratype for Amphisamytha galapagensis Zottoli, 1983
Catalog Number: USNM 81289
Collection: Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology
Preparation: Alcohol (Ethanol)
Collector(s): Woods Hole Oceanographic Institution
Year Collected: 1979
Locality: Galapagos Rift, Garden Of Eden, Galapagos Islands, Ecuador, North Pacific Ocean
Depth (m): 2485 to 2485
Vessel: Alvin DSR/V

Holotype for Amphisamytha galapagensis Zottoli, 1983
Catalog Number: USNM 81288
Collection: Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology
Preparation: Alcohol (Ethanol)
Collector(s): Woods Hole Oceanographic Institution
Year Collected: 1979
Locality: Galapagos Rift, Rose Garden, Galapagos Islands, Ecuador, North Pacific Ocean
Depth (m): 2451 to 2451
Vessel: Alvin DSR/V

	The smallest Amphisamytha larvae fall in the size range of the nectochaetes. Nectochaete larvae have a ciliary band circling the body near the anterior end (at right in photo) and are generally thinner for their length than Amphisamytha.
	Ophryotrocha larvae are similar in size and general outline to Amphisamytha, but have a prominent jaw apparatus visible through the body wall. Their parapodia are also more prominent than those of Amphisamytha.

Depth range based on 111 specimens in 1 taxon.
Water temperature and chemistry ranges based on 104 samples.

Environmental ranges
  Depth range (m): 1519.5 - 3660
  Temperature range (°C): 1.629 - 2.931
  Nitrate (umol/L): 21.028 - 43.603
  Salinity (PPS): 34.493 - 34.944
  Oxygen (ml/l): 1.130 - 5.742
  Phosphate (umol/l): 1.396 - 3.060
  Silicate (umol/l): 34.435 - 177.173

Graphical representation

Depth range (m): 1519.5 - 3660

Temperature range (°C): 1.629 - 2.931

Nitrate (umol/L): 21.028 - 43.603

Salinity (PPS): 34.493 - 34.944

Oxygen (ml/l): 1.130 - 5.742

Phosphate (umol/l): 1.396 - 3.060

Silicate (umol/l): 34.435 - 177.173
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.