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constantly outdated shark taxonomy page, a monster list of shark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 of elasmodiver.com that contains pictures of
other marine organisms and of marine habitats. This expansion of
Elasmodiver is in its first stages but will eventually include pages
on all types of marine mammals, bony fishes and marine invertebrates
as well as coastal habitats, reefscapes and other imagess relating
to the ocean. Please return regularly to enjoy the progress.
Spiny
dogfish, Common spiny dogfish, Piked dogfish, Mud shark.
Latin Name: Squalus acanthias
Family: Squalidae
Identification: Long,
flattened, pointed snout. Grey to brown above usually with small white spots.
White spots may follow lateral line. Eyes large. Mildly venomous spines on
first and second dorsal fins. Anal fin absent. Belly white.
Size: Maximum
length 1.6 meters. size at birth 22-33 cm. Maximum recorded age 66 years.
Habitat: Often
cruise over sand
and mud bottoms. Also frequently encountered over rocky reefs. From 0 to 900 meters.
Inhabits estuarine, coastal and offshore waters sometimes migrating over great distances Newfoundland tagged individuals have been captured years later in Iceland.
Normal migration patterns are usually more localized; Western Atlantic groups migrate between Canada and the US.
Abundance and distribution:
North and South Atlantic Ocean and South Pacific and Southern Ocean around
Australia. Some populations may eventually be recognized as new species or
distinct 'sub species'. An example of this is the recent resurrection of the
North Pacific spiny dogfish Squalus
suckleyi.
The spiny dogfish's western range extends along the
east coast of North America from Labrador to the Gulf of
Mexico. Some populations arelocallyabundant
while others have experienced steep declines leading to drastically reduced
fishing quotas (especially in Europe). In the UK and Europe Spiny dogfish are
the principal fish utilized in "fish and chips". They are also ground up to
be used in fertilizers.
Behavior: Cruises
over soft bottoms either alone or in small groups. Occasionally schools (often
segregated by sex) in response to food supply such as squid or salmon runs. May also
form schools with other species such as leopard sharks and smoothhounds. Diet
consists mainly of bony fishes. Other foods include octopus, squid and
crustaceans.
Reproduction: Ovoviviparous.
Litter size from 1- 20. Spiny dogfish have a slow maturity rate (around 12 years) which makes them very vulnerable to
over fishing. They also have the longest gestation period of any known
vertibrate 18-24 months.
Reaction to divers: These
are curious and harmless sharks that will often closely approach divers and on
occasion accompany them on their dives. If divers are buzzed by a dogfish they can
often be recalled by tapping two stones together. The dogfish seem to find this irresistible
and will repeatedly return to satisfy their curiosity. If engaging in dogfish
feeds it is possible to play tug of war with these little sharks. Care should be
taken to avoid their mildly venomous spines.
Diving logistics:
Spiny dogfish are sometimes attracted to inshore shark feeds organized in New
England.
As spiny dogfish
schools are reported to reach plague like proportions in some areas, it may be
possible to easily attract quite large numbers although the appearance of the
schools is hard to predict. If planning to chum, try the summer months when the
Gulf Stream has moved in towards shore.
Resurrection and redescription of Squalus suckleyi (Girard,
1854) from the North Pacific, with comments on the Squalus acanthias subgroup (Squaliformes:
Squalidae) DAVID A. EBERT 1, 2, 3, 8, WILLIAM T. WHITE 4, KENNETH J. GOLDMAN5, LEONARD
J.V. COMPAGNO6, TOBY S. DALY–ENGEL7 & ROBERT D. WARD4
Migration Patterns of Spiny Dogfish (Squalus
acanthias) in the North Pacific ocean - G.A. McFarlane and J.R. King. -
Fisheries and Oceans Canada.
Reef Sharks and Rays of the World
- Scott W. Michael.
Marine life of the North Atlantic
- Andrew J Martinez - Down East Publications.
