OCEANOGRAPHY & MARINE SCIENCE

An extensive series utilizing many multiple
images to present a comprehensive and
integrated approach to the total spectrum
of marine biology and oceanography. Solid
science wonderfully detailed!

MARINE COMMUNITIES
The distribution and adaptation of marine plants and animals world-wide and the in- fluence of water depth and the nature of the bottom. 5 pgms.105 slides and guides.
EPSS-0810X SLIDES
$179.95

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SAVE OVER $67.00 ON 5 SLIDE SET BUNDLE ORDER EP #SS-0810X.........$179.95
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BIOGEOGRAPHY & EVOLUTION Slides order #SS-0810S........$49.95

Presents an investigation of the world-wide distribution of plants and animals,
and the role of ecological, geographical and historical factors in that distribution. Looks
at the selective pressures emanating from the combination of these three factors and
subsequent effects on contemporary plants and animals. Offers a synthesis of terrestrial
and marine biogeography as essential to the study of evolution. 20 frames, cassette and
guide. (Filmstrip order SS-0810F......$15.00.)

CONTENT SAMPLE: 3. The different species compositions of contemporary commun-
ities can be correlated with their ecologies and geographies, but to explain these distributions a
third factor--their histories--must also be considered. All life has continuity, and evolution is a
history of adaptations made by organisms as their physical and biological environments change
with time. Different species are generally not distributed evenly over the surface of the earth; few
are cosmopolitan, and most are restricted to specific geographic regions by physical barriers of
one kind or another. These barriers and their historical effects on the geographic distribution of
life are the subjects of this program.

A striking example of convergent evolution is shown by great auks and penguins, large
flightless seabirds that evolved independently in cooler waters of the Northern and Southern
Hemispheres, respectively. Great auks (Pinguinus impennis) were once abundant on Iceland
and other North Atlantic coastlines but became extinct due to overhunting in the mid-eighteenth
century. The name "penguin" was originally applied to these flightless, swimming sea birds
(left). The true penguins (right), are restricted to oceans of the Southern Hemisphere and hence
did not overlap in range with the great auks. The warm tropics presumably served as a barrier
that restricted each to its home waters.

They are only very distantly related--auks have closer affinities to puffins and gulls, while
penguins seem to be related to albatrosses and petrels--yet each evolved body forms that
adapted them to similar ecological roles in their respective communities. Both are flightless birds
with flipper-like wings that are used for swimming underwater in pursuit of fish and invertebrate
prey.
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INTERTIDAL COMMUNITIES Slides order #SS-0840S.......$69.95

Focuses on the intertidal zone, one of the most unique habitats on earth. Three
general types of intertidal communities, rocky intertidal, sand beaches, and mud flats,
are considered. The distribution of life within these intertidal zones, as it varies in
accordance with the alternating marine and terrestrial character of a community, is
discussed. 40 frames, cassette and guide. (Filmstrip order SS-0840F......$15.00.)

CONTENT SAMPLE: 4. The intertidal zone is roughly defined as the area along the
shore that is bounded by the highest high tides and the lowest low tides. A splash zone above
the highest high tide mark and the subtidal zone just beyond the most seaward recessions of
the low tides support transitional communities.

Actually the intertidal zone itself may be viewed as a series of transition zones
containing marine plants and animals which are in the process of adapting to the semiterrestrial
conditions of the shore. Evolution occurs at such imperceptible rates that we sometimes forget it
is an ongoing, open-ended process. The slow landward march of intertidal organisms probably
parallels the paleozoic invasion of the land. Avoidance of marine predators has perhaps been a
significant selective pressure that fostered both migrations. Some periwinkle snails and
beach-hopper crustaceans have successfully migrated beyond the confines of the intertidal zone.
The land is no longer an unexploited habitat, however, and today’s intertidal organisms must deal
with terrestrial predators, notably shore birds.

Intertidal organisms must adapt to two major environmental fluctuations: the alternate
flooding and inundation of the intertidal zone with seawater and the temperature extremes that
result, especially at low tide. As noted above, the vast majority of intertidal animals are marine.
Breathing in an aqueous environment seems to be an insurmountable obstacle to most terrestrial
animals. Even in estuaries most of the animals are marine forms; the salinity of seawater seems
to be a potent barrier to freshwater animals. Marine organisms must avoid desiccation in the
intertidal zone; they must keep their respiratory organs and other tissues moist. They must also
be able to withstand or avoid the extreme temperature variations that are sometimes encountered
during low tide.

A gradient of exposure exists in the intertidal zone. The most landward margin is
uncovered first by the receding tide and inundated last by the rising tide. Organisms in this upper
zone must be able to withstand longer intervals of exposure than those on the seaward margin.
Three general zones are recognized within the intertidal: an upper intertidal zone, a middle
intertidal zone, and a lower intertidal zone. Each is characterized by a different exposure regime,
and each is populated with a distinct array of organisms adapted to those conditions. This
zonation of intertidal life is most conspicuous and sharply defined on rocky shorelines, but is
equally characteristic of other intertidal communities as well.
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SUBTIDAL COMMUNITIES Slides order #SS-0845S.......$42.50

The rich diversity of marine organisms supported in the subtidal zone--that zone
extending seaward from the level of the lowest tide--is explored. Examines the abundant
supplies of nitrates and phosphates contributing to the high productivity of subtidal
communities. Considers the various plant and animal forms living in these communities.
15 frames, cassette and guide. (Filmstrip order SS-0845F.....$15.00.)

CONTENT SAMPLE: 1. The subtidal zone extends seaward from the level of the
lowest low tide. This zone is never exposed by the receding tide and supports a rich diversity of
marine organisms. The seaward margin of the subtidal zone is arbitrarily set at one hundred
meters or one hundred fathoms by some authors; others suggest that the subtidal zone extends
to the edge of the continental shelf. The latter is perhaps the best limit. The continental shelf
slopes gently at about 10 feet per mile for an average distance of 42 miles from the shore before
plunging precipitously to the deep-ocean floor.

Since the subtidal zone is always submerged, its temperature and salinity are more
constant than the intertidal zone and its life zones are less pronounced. Subtidal zonation
depends less on depth than on light attenuation and the composition of the bottom.

The distribution of seaweeds in the subtidal zone depends upon the degree of light
penetration through the often turbid coastal waters. Different algal groups possess various arrays
of photopigments that equip them to capture different wavelengths of light and many bear air filled
structures that float them into the more highly illuminated surface waters.

The distribution of benthic animals in the subtidal zone depends upon the type of local
substrate. Rocks and seaweeds provide attachment sites for many sessile invertebrates, while
gravels, sands and muds are populated by burrowing forms. Benthic animals may be subdivided
into the epifauna (those that attach to or crawl over the surface of the substratum) and the
infauna (those animals that live within the substratum). Pelagic animals are free-swimming
forms, primarily fish, while planktonic plants and animals drift passively in the water currents.

As this diagram indicates, the continental shelves occupy only about 7% of the ocean
floor. However, most of the world's most productive fishing grounds are located in these highly
productive areas.
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PELAGIC COMMUNITIES Slides order #SS-0830S........$42.50

The existence of pelagic animals in the upper photic zone, the second level
dysphotic zone, and the eternally dark aphotic zone is explored. Types of free-swimming
animals living in each zone are studied and the promise of future exploration of the
ocean depths is discussed. 15 frames, cassette & guide. (Filmstrip SS-0830F...$15.00.)

CONTENT SAMPLE: 12. Intermediate waters are also the home of the only truly
pelagic invertebrates: the squid, cuttlefish and their allies. These molluscs are distant
relatives of the snails, sea slugs, clams, oysters and tusk shells. Unlike the proverbially slow
snail, however, squid are among the fastest swimmers in the ocean over short distances. One
aspect of their body plan that enhances locomotion is the almost complete reduction of the shell.
Only a horny internal pen remains. Squid are not only one of the most highly advanced
molluscs but among the most complex invertebrates as well.

The mantle, which secretes a calcareous shell in most other molluscs, has become
specialized for locomotion. Water is drawn into the mantle cavity at several points around the
edges of the mantle near the head and foot. Powerful circular muscles in the mantle wall then
contract, thereby reducing the volume of the mantle cavity. An ingenious set of valves prevents
water from escaping anywhere except through the ventral funnel, which delivers a jet of water that
propels the squid through the water. Alternate contractions and relaxations of the mantle
muscles empty and fill the mantle cavity, propelling the squid through the water like a rocket.

Squid are active predators that feed mainly on fish and smaller squid. A well-known
ability of squid is their capacity to release a cloud of dark ink into the water when disturbed. This
forms a "smoke screen" which camouflages their escape, while probably interfering with the
chemoreceptors of predators as well. The deep sea squid (left) has no ink, but when excited
shoots out a cloud of luminescent fluid! Squid range in size from two inches to 50 ft in length.
The largest deep-water squid are known only from dead examples that are occasionally washed
ashore, or from their remains recovered from the stomachs of their predators, the sperm whales.
The largest squid recovered (Architeuthis princeps) had an overall length of 55 ft, 35 ft of which
was tentacles. Shown here (upper right) is a common pelagic squid, Loligo opalescens.

Cuttlefish (lower right) are relatives of the squid that are common in the deep waters of
most oceans. They differ from squid in having an internal shell, or spongy cuttlebone. Cuttlefish
range in size from several inches to about six feet in length. They consume fish and are in turn
preyed upon by the toothed whales.
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BENTHIC COMMUNITIES Slides order #SS-0835S.......$42.50

The investigation of ocean depths and the living organisms found with each new
exploration method. Discusses continental shelves and life in the abyss. Introduces
deep-sea regions and shallow tropical waters as habitats with stable physical conditions
and high biological diversity. 15 frames, cassette & guide. (Filmstrip SS-0835F....$15.00.)

CONTENT SAMPLE: 10. This chart summarizes some of the differences between
conditions on the continental shelves and the abyssal plains. The average width of the continental
shelves is about 65 km (40 mi). At an average depth of about 130 m (425 ft) the slope steepens
rather abruptly at the shelf break. From this point the bottom slopes steeply to the ocean floor,
some 4,000 m or so below.

Just as their depths differ greatly, so too do the physical conditions on the bottoms of
continental shelves and the abyssal plains. The waters overlying the shelves are within the
photic zone. Seasonal fluctuations in these coastal waters recycle nutrients within the photic
zone and contribute to the autotrophic production of phytoplankton and, where the bottom rises
within the photic zone, of benthic algae. Primary production is especially high in polar and
temperate waters that experience seasonal thermocline turnovers and along the western coasts
of continents where wind-driven upwellings occur. The productive areas are the locations of the
world's greatest fisheries; for example, the George's Banks off Newfoundland and the coastal
waters of Peru.
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~0202-64~ Brachiopod. photo by Charles R. Belinky, Ph.D.

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