Shorefishes of the Eastern Pacific online information system

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Species: Platyrhinoidis triseriata, the Thornback, Thornback guitarfish

All Families:   All Genera:   All Species:

snout short, round
disc: width > length
tail: 3 rows hooked spines



Platyrhinoidis triseriata (Jordan & Gilbert, 1880)

Thornback, Thornback guitarfish

Disc broad, oval, width about equal to length; blunt round snout; rostral cartilages wide apart at base, converging rapidly; eyes small, wide apart; large spiracle behind each eye; skin uniformly covered with small granules; 4 strong spines at snout tip; 4-5 blunt spines around each eye; 3 median rows of large hooked spines on tail, the central one extending onto the disc behind the head; a small patch of spines on each shoulder and another on the disc to the side of each eye;  2 large equal sized dorsal fins, towards rear of tail; tail thick, sides vertical, with elongate oval fin.

Grey-brown to olive-brown upper surface, white ventral surface.

Size: 91 cm.

Habitat: benthic on fine sand to mud bottoms, off beaches, in sheltered muddy bays.

Depth: 0-137 m.

California to the Gulf of California.

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  • Marine Only
  • Marine
  • Inshore
  • Inshore Only
Water Column Position
  • Bottom
  • Bottom only
  • Mud
  • Soft bottom only
  • Sand & gravel
  • Soft bottom (mud/sand/gravel/beach/estuary/mangrove/seagrass)
FishBase Habitat
  • Demersal
Feeding Group
  • Data
  • Carnivore
  • Mobile benthic worms
  • Mobile benthic gastropods/bivalves
  • Octopus/squid/cuttlefish
  • Mobile benthic crustacea (shrimps/crabs)
  • Data
Egg Type
  • Live birth
  • No pelagic phase
  • No data
  • No pelagic larva
Global Endemism
  • East Pacific endemic
  • TEP non-endemic
  • All species
Regional Endemism
  • Continent
  • California province, primarily
  • All species
  • Continent only
  • Tropical Eastern Pacific (TEP) non-endemic
  • Temperate Eastern Pacific, primarily
  • Vagrant
Climate Zone
  • Northern Subtropical (Cortez Province + Sinaloan Gap)
  • North Temperate (Californian Province &/or Northern Gulf of California)
IUCN Red List
  • Least concern
  • Listed
  • Not listed
Length Max
  • 91
Depth Range Min
  • 0
Depth Range Max
  • 137