Not just Shark
Pictures: Elasmodiver contains photos of sharks, skates, rays, and
chimaera's from around the world. It began as a simple web based
field guide to help divers find the best places to encounter
different species of sharks and rays but it has slowly evolved into
a much larger project containing information on all aspects of shark
diving and photography. There are now more than a thousand shark
pictures and sections on shark evolution, biology, and
conservation. There is a large library of reviewed shark books, a
constantly outdated shark taxonomy page, a monster list of shark
links, and deeper in the site there are numerous articles and
stories about shark encounters. Elasmodiver is now so difficult to
check for updates, that new information and pictures are listed on
an Elasmodiver Updates Page that can be accessed here:
If you're looking for a
broader range of marine life pictures the following links represent
a new area that contains pictures on other marine organisms and on
marine habitats. This expansion of Elasmodiver is in its first
stages but will eventually include pages on everything from sea
stars to nudibranchs. Creating this portal will take time and for
now it consists of a token offering of fish pictures. Please return
regularly to enjoy the progress.
Identification:
Disc width considerably greater than disc length.
Tail shorter than disc. Anterior edges of pectoral fins concave with indistinct
convexity level with head. Posterior edges of pectoral fins broadly convex.
Snout pointed. Dorsum light brown with darker,
evenly scattered, round spots. One dark ocelli ringed with yellowish tan may be
visible on each wing. Spots occasionally less uniform and ringed with pale lines
that form a reticulated pattern over the entire disc.
Distinct,
paired, converging lines of reddish brown rostral cartilage on snout. No line of
thorns (enlarged dermal denticles) along midline of back. Three rows of thorns
on tail. Ventrum off white fading to lavender/grey at margins.
Size: Maximum
length 152cm
Habitat:
The barndoor skate inhabits sandy, gravel and mud bottoms
from inshore to 430m but there are records from as deep as 1600m.
Abundance and distribution: North
western Atlantic Ocean from the Grand Banks and St Lawrence River in
Canada to North Carolina. Catch records from the Labrador shelf indicate that
the barndoor's range may be considerably larger than previously thought.
Diet:
Bivalves, squids, lobsters, shrimps, worms and benthic fishes.
Behavior:
poorly known.
Reproduction:
Oviparous. egg cases deposited on sand and mud flats.
A captive female
barndoor skate at the Montreal Biodome laid 115 egg cases in 2007. Hatching
occurred throughout the year. Incubation took between 342 and 494 days. The
emerging skates averaged 193 mm in length (128 mm disk width) and weighed 32 g.
Vulnerability: The barndoor
skate is considered endangered by the IUCN. Although this species is not the
focus of a directed fishery it is regularly caught in trawling/dredging operations
targeting deep sea fishes, scallops and squid among other species. Catch rates in US waters declined
by a staggering 96 to 99% between 1960 and 1990.
NOAA catch data
suggests that the species is now recovering and is no longer over fished. It
remains vulnerable to depletion if managed incorrectly.
Photographs:
Kings Beach, Rhode Island. Specimen released from
bycatch collected while trawling for squid. Images were made possible through
the kind cooperation of Brian Raymond.
Similar species:
There are a number of other skates inhabiting this region. Identification in the
field is easiest by noting the barndoor skate's unique body shape (smoothly
concave leading edges of the disc which is wider than long) combined with its
pattern of dark evenly spaced black spots. Note however that the barndoor's
markings can be variable as illustrated by the image below:
Image courtesy of
Brian Raymond
Reaction to divers:
Swims away when closely approached.
Diving logistics:
The barndoor skate generally inhabits depths
exceeding normal diving limits. On rare occasions this skate has been seen at
dive sites in Eastern Canada. There is also an unconfirmed report of a barndoor
showing up at Back Beach near Rockport, Cape Anne, Massachusetts.
