Discover Florida Nature
It's time to explore the natural Florida
 Florida
Marine Mammals: Dolphins (2) |
|
|
|
 Risso's
Dolphin-Risso's dolphins are a relatively robust dolphin with a
rounded head, similar in shape to the more familiar pilot whale. They
have an unusual external vertical crease in the melon (the organ in the
rounded head used to direct sonar clicks) that runs from the front of
the forehead to the mouth. Adult Risso's dolphins are usually dark gray
with extensive white scarring. The scars can be scratches, splotches, or
circular marks and, in some animals, can be so extensive that the entire
body appears to be white. This scarring may come from bites from other
Risso's dolphins, squid bites, or parasites. As calves, their bodies are
a uniform light gray, which then darkens to a brownish-gray in
juveniles. Risso's dolphins also have a white anchor-shaped patch on
their ventral/chest area (from throat to stomach). Reflecting the
offshore distribution of this species, primary prey appears to be squid,
although they have also been known to feed on a number of fish species.
While the size of their squid prey is unknown, squid beaks from species
that grow up to 12 feet in length have been found in the stomachs of
stranded Risso's dolphins. Risso's dolphins tend to prefer offshore
habitats worldwide in the warm temperate and tropical waters of both
hemispheres. Rough-toothed
Dolphin-
The rough-toothed dolphin is named for the 20-27 teeth with faint ridges
located in both the upper and lower jaw. Color varies by region within
the species, but generally they are dark gray with light spots on the
flanks. The ventral side, lower jaw and lips are white and they have a
darker marking that extends over the eyes to the upper part of the
flanks. Like other marine species, rough-toothed dolphins may show scars
resulting from encounters with other marine life such as sharks, squid,
and other rough-toothed dolphins. Rough-toothed dolphins are small
members of the dolphin group that reach a length of 8.5 feet and weight
of 350 pounds Like other dolphins, rough-toothed dolphins communicate
and echolocate using clicks and whistles. Reproductive biology is poorly
known in this species, but it is known that maturity occurs at 11 years
of age and maximum longevity is 32 years. Rough-toothed dolphins usually
occur in tight-knit groups of 10 to 20. Rough-toothed dolphins
apparently feed primarily on squids and fishes. Spinner
Dolphin- So called for their high, spinning leaps, spinner
dolphins are known as playful, eager bow-riders. Spinner dolphins are
found in the Atlantic, Indian and Pacific Oceans, where they are
restricted to tropical, subtropical and less often warm, temperate
regions. Spinner dolphins are characterized by a long slender beak with
a black tip and black lips, and an erect dorsal fin. The body is mainly
grey, with a three toned coloration. Adult spinner dolphins are about
5.9 -6.6 feet in size and weigh 165-209 pounds. Spinner dolphins often
associate with spotted dolphins, common dolphins and small to medium
sized whales. Spinner dolphins typically congregate together in groups
or pods. These groups however are not really comparable to those formed
by other mammals. The society is leaderless and very fluid. Associations
change daily and there is no strict hierarchy of dominance. In each
group however there is usually a core of individuals who associate on a
regular basis.  Striped
Dolphin-Striped dolphins are the most widespread dolphins in
the world. These dolphins can reach lengths of about 9 feet and weigh up
to 350 pounds. They have a small to medium-sized robust, sleek body with
a long, defined beak and round "melon" (forehead). Their distinct and
striking coloration pattern with a complex of bold thin stripes is the
origin of its common name. Calves and juveniles may have more muted
colorations and patterns. Striped dolphins are usually found in tight,
cohesive groups averaging between 25 and 100 individuals, but have been
occasionally seen in larger groups of up to several hundred and even
thousands of animals. Within these schools there is a complex system of
individuals that may be organized by age, sex, and breeding status. They
rarely associate with other species of whales, dolphins, and seabirds.
Their surface behavior is often characterized as sociable, athletic,
energetic, active, and nimble with rapid swimming. They can often be
observed breaching, "roto-tailing", jumping, and leaping up over 20
feet above the surface of the water. Striped dolphins feed on a diverse
diet consisting of various species of relatively small, closely-packed
schooling fish such as cod, squid and octopus.
|
|
 Follow
us on Facebook  Follow
us on Twitter Advertise | Privacy Statement | Contact | Alaska Nature | Michael Arnold Art| Dog Encyclopedia | Dog Encyclopedia| |
|
