Download OL OOP Section 06

0
OUR OCEAN PLANET
OUR OCEAN PLANET
SECTION 6 – TEMPERATE SEAS
1
REVISION HISTORY
Date
Version
Revised By
Description
Aug 25, 2010
0.0
VL
Original
6. TEMPERATE SEAS
6. TEMPERATE SEAS
2
6. TEMPERATE SEAS
Temperate seas lie between the tropics and the polar regions.
These are cool green waters that are highly productive and
immensely rich in algae, plant, and animal life.
Summers are warm and winters cold but there is rarely permanent
sea ice in temperate waters. Water temperatures range from 4°C20°C (39°F-68°F).
The algae and plant life that makes these seas green comes from
chlorophyll found in several organisms namely:
1. Plankton
 Phytoplankton – plant and algae plankton
 Zooplankton – animal plankton
2. Marine Algae/Seaweeds
 Green
 Brown
 Red
The rich algae and plant life base gives rise to large numbers of
zooplankton (e.g. copepods), herbivorous invertebrates (such as sea
urchins and molluscs), and herbivorous fish.
These primary
consumers are preyed upon by other invertebrates (e.g. jellyfish,
horseshoe crabs), fishes (e.g. sturgeons), birds, and mammals (e.g.
sea otters and sea lions).
3
6. TEMPERATE SEAS
4
6.1 PLANKTON
6.1 PLANKTON
5
6.1 PLANKTON
6.1 PLANKTON
Plankton is a general term used to refer to a variety of tiny animals
and plants that are found drifting about in the ocean.
There are two main types of plankton, namely, phytoplankton (plant
plankton) and zooplankton (animal plankton). They are usually
microscopic in size although some can be quite large (a couple of
meters in diameter).
Each year, between spring and autumn, plankton numbers increase
dramatically to form huge populations. These planktonic blooms are
critical to vast numbers of invertebrates, fish, birds and mammals,
since plankton is one of the most fundamental and important
sources of food in the ocean.
6.1.1 Phytoplankton
Phytoplankton (plant plankton) can use sunlight to transform carbon
dioxide and water into carbohydrates through a process called
photosynthesis. Phytoplankton are, therefore, producers and form
the base of the ocean’s food chain.
There are several types of phytoplankton varying greatly in size and
shape:
6
7
6.1 PLANKTON
1. Cyanobacteria
Cyanobacteria are the smallest of the phytoplankton and are tiny
single-celled organisms that have blue and green pigments. This
gives them their common name – the blue-green bacteria or bluegreen algae.
2. Diatoms
Diatoms are beautiful single-celled algae with two glass-like halves
and spines and ribs radiating from them. There are over 6,000
species of diatoms, and they are often the most numerous
phytoplankton in temperate waters.
3. Dinoflagellates
The dinoflagellates have both plant and animal characteristics in that
they are able to photosynthesize food (like plants) but can also move
using flagella (like animals). Their bodies are made of cellulose and
they can produce bioluminescent light.
4. Protozoans
Protozoans are single-celled animals. However, some protozoans
contain symbiotic algae which are able to photosynthesize food.
Protozoans such as foramniferans have shells made of calcium
carbonate while radiolarians have shells made of silica.
Important!
Each year, 6 billion tonnes of
microscopic algae, such as
diatoms, grow in the world’s
oceans producing nearly 50% of
the world’s oxygen – a byproduct of photosynthesis.
8
6.1 PLANKTON
REFERENCES & FURTHER READING
Byatt, Andrew, Fothergill, Alastair and Holmes, Martha, The Blue
Planet: Seas of Life, Chapter 4, DK Publishing Inc., (2001), ISBN 07894-8265-7
Interesting!
The word plankton comes from
the Greek word “planktos” which
means “drifter” or “wanderer”.
9
6.1 PLANKTON
6.1.2 Zooplankton
Zooplankton (animal plankton) feed on phytoplankton or other
zooplankton. There are several types of zooplankton, namely:
1. Copepods
Copepods ("oar feet") are small, shrimp-like crustaceans with Tshaped antennae that swim in seas, lakes and ponds. These are
the primary consumers of phytoplankton. They have a hard
exoskeleton, legs for swimming and gathering food, a segmented
body, and jointed appendages. Most copepods are less than 1 mm
(0.04 in) long but a few oceanic species are over 1 cm (0.25 in) long.
These arthropods have one simple eye in the middle of the head
which can only differentiate between light and dark. There are two
pairs of antennae; one pair is long and one pair is short. Female
copepods produce clusters of eggs that she carries in one or two
egg sacs that are attached to her abdomen. Like all crustaceans,
copepods molt their exoskeleton as they grow. There are 10 orders
and over 4,500 species of copepod. A few orders are freeswimming (using their legs) but many are parasites (of fish).
Copepods are adept at catching and eating phytoplankton including
cyanobacteria, diatoms and other tiny, single-celled organisms in the
water. Maxillae, maxillipeds and antennae push food towards the
mandibles (jaws) for processing.
Important!
Copepods are probably the most
numerous animal on the planet
forming 70% of the total
zooplankton.
Interesting!
The collective name for a group
of plankton is a “swarm”.
6.1 PLANKTON
10
Free-swimming copepods are a component of zooplankton and are very important in the food web since
many animals feed on them including mussels, fish and fish larvae, squid, sea birds, and mammals
(such as baleen whales and certain seals).
2. Meroplankton
Meroplankton is the collective name for the tiny eggs and larvae of animals that spend part of their life in
the plankton before maturing. In summer, the sea will be full of eggs, larvae and young invertebrates.
The young of crustaceans (e.g. crabs, lobsters & shrimps), echinoderms (sea urchins & sea stars),
molluscs, and fish are among the huge variety of organisms that spend their first weeks of life as
plankton. Many meroplankton are herbivores. In time, they will change in appearance and, if the larvae
are fortunate, they will survive to adulthood.
3. Cnidarian Larvae
Other zooplankton include free-swimming cnidarians such as jellyfish. For example, moon jellyfish
primarily feed on copepods and can consume thousands in a day. These jellyfish form swarms so dense
that the water can appear pinkish-white from the air. In contrast, lion’s mane jellyfish feed on copepods,
meroplankton, other jellyfish, and fish, but do not tend to form swarms.
Zooplankton is, in turn, preyed upon by other animals, ranging from other invertebrates and small fish to
the giants including planktivorous sharks (e.g. whale and basking sharks) and baleen whales (e.g.
humpback and blue whales).
REFERENCES & FURTHER READING
http://museumvictoria.com.au/crust/copbiol.html - Copepods
http://en.wikipedia.org/wiki/Plankton - Plankton
6.2 MARINE ALGAE / SEAWEED
6.2 MARINE ALGAE / SEAWEED
11
6.2 MARINE ALGAE / SEAWEED
6.2 MARINE ALGAE / SEAWEED
Seaweeds are marine algae and, although they are found virtually
worldwide, most of the world’s 10,000 species of seaweed exist in
temperate water. The smallest can be planktonic or found growing
in sand or inside an animal’s shell or body. The most familiar,
however, are probably the large seaweeds which are often found on
rocky coasts firmly attached to a hard stable substrate.
At the base of the seaweed is a clump of entwined growths, called a
holdfast, which anchors the seaweed to the substrate. From the
holdfast, a long stem called a stipe extends upwards which supports
a series of leaf-like fronds (or “blades”) in which most photosynthesis
occurs. In the largest seaweeds, the fronds are buoyed by gas-filled
bladders called pneumatocysts.
The specific colours and forms of seaweed depend on their habitats
and combination of pigments. Generally, however, there are three
types of marine algae – green, brown and red.
1. Green Algae
Green algae get their colour from the green pigment chlorophyll.
They are about 6,000 species of green algae but most are not found
in the ocean. The marine species are commonly found in temperate
rock-pools. They are generally small and many are filamentous
resembling thin green hair. One of the most common is sea lettuce,
which is found in rock-pools and around the bases of larger
seaweeds. Sea lettuce is often eaten by small invertebrates.
12
13
6.2 MARINE ALGAE / SEAWEED
2. Brown Algae
There are about 1,500 species of brown algae varying from
yellowish to deep brown. They range from simple filamentous algae
to the largest seaweed of all – the giant kelp (Macrocystis spp.)
which may grow to more than 45 m (150 ft) in length. Although giant
kelp superficially resembles a tree, it is quite different. For example,
kelp has no roots. Kelp does anchor itself to the bottom of the
ocean floor but the anchoring system (“holdfast”) does not take in
nutrients from the soil like plant roots do. The stipe and blades of
the kelp are very flexible and cannot stand upright unaided. As a
result, kelp has tiny air bladders at the base of each blade to help it
float and grow toward the surface of the water where sunlight is Interesting!
most plentiful.
Seaweed is an integral part of
3. Red Algae
Red algae are the most numerous of the marine algae and consist of
about 4,000 species. They contain chlorophyll but the green colour
is masked by a red pigment called phycobilin. They are usually
small and tissue-like, and encrust rock pools or grow on larger
brown seaweed stipes. They can be a variety of colours from pink to
purple. Some red algae deposit thick calcium carbonate (the same
material coral is made from) around their cells walls. These coralline
red algae are tough enough to grow in the rocky surf zone.
human life. Kelp, sea lettuces and
red algae are dried, steamed, and
cooked in a variety of dishes. The
thin black sheets covering rice and
raw fish in sushi is made from red
algae Porphyra. Alginates from
brown seaweed are used to give ice
cream its smooth texture. Agar,
from red algae, is used in cake
icings, as a clarifying agent for beer
and as a growth medium for microorganisms studied by scientists.
6.2 MARINE ALGAE / SEAWEED
14
6.2.1 Kelp Forests
Kelp provides the physical substrate and habitat around which kelp forest communities are built.
Organisms supported by kelp forests include sea urchins, sea stars, sea anemones, clams, and
tunicates. These organisms are preyed upon by larger animals such as fish and octopuses. Sea otters
and sea lions also eat sea urchins, clams and octopuses. These mammals may, in turn, be preyed upon
by large sharks, such as the great white shark.
Kelp forest ecology studies focus on understanding bottom-up and top-down trophic processes – the
relationships between organisms and their place in the food chain.
Bottom-up processes are generally driven by abiotic conditions required for primary producers to grow
(such as the availability of light and nutrients). For example, the occurrence of kelp is frequently related
to oceanic upwelling zones which provide unusually high concentrations of nutrients to the local
environment. This allows kelp to grow and support herbivores which, in turn, support consumers at
higher trophic levels.
In contrast, top-down processes are those in which predators limit lower level prey species through
feeding on them. In the absence of predation, the lower level species would flourish. For example, in
Alaskan kelp forests, sea otters control populations of herbivorous sea urchins through predation. When
sea otters are removed from the ecosystem (for example, by human activity), sea urchin populations are
released from predatory control and grow dramatically. This leads to increased herbivore pressure on
local kelp stands.
6.2 MARINE ALGAE / SEAWEED
15
Deterioration of the kelp itself results in the loss of the physical ecosystem structure and subsequently,
the loss of other species associated with this habitat. In Alaskan kelp forest ecosystems, sea otters are
the keystone species that mediate this trophic cascade. In Southern California, kelp forests persist
without sea otters and the control of herbivorous sea urchins is instead mediated by other predators
including lobsters and large fishes. The effect of removing one predatory species in this system differs
from Alaska because there are other predators that can continue to regulate sea urchins. However, the
removal of multiple predators can effectively release sea urchins from predator pressure and allow kelp
forest degradation.
While sea urchins are usually the dominant herbivore, others include sea stars, isopods, kelp crabs, and
herbivorous fishes. In many cases, these organisms feed on kelp that has been dislodged from
substrate and drifts near the ocean floor. If there is enough drift kelp, herbivorous grazers do not exert
pressure on attached plants. Many studies in Southern California have demonstrated that the availability
of drift kelp specifically influences the foraging behavior of sea urchins. Drift kelp and kelp-derived
particulate matter have also been important in subsidizing adjacent habitats, such as sandy beaches and
the rocky inter-tidal areas.
REFERENCES & FURTHER READING
http://www.nmnh.si.edu/botany/projects/algae/classification.htm - Algae
http://www.usc.edu/org/seagrant/Education/Kelp/WhatIs.html - What is kelp?
http://en.wikipedia.org/wiki/Kelp_forest - Kelp forest
http://www.amonline.net.au/factsheets/kelp.htm - Kelp fact sheet
http://news.nationalgeographic.com/news/2006/09/060906-octopus-video.html - octopus/shark
Byatt, Andrew, Fothergill, Alastair and Holmes, Martha, The Blue Planet: Seas of Life, Chapter 4, DK
6.2 MARINE ALGAE / SEAWEED
6.2.2 Kelp Forest Life
16
6.2 MARINE ALGAE / SEAWEED
KELP
Kelp is a brown seaweed. Perhaps the most widely-recognized
species are the giant kelps (Macrocystis spp.) although there are
numerous other types. Macrocystis pyrifera grows to over 45 m
(150 ft) long. The stipes (or stems) are unbranched and each has a
gas bladder at its base. When a large number of giant kelp grows
together, as they do off the coast of California, they are collectively
known as a “kelp forest”.
SEA OTTER
Sea otters are long, sleek and furry marine mammals. They are the
largest member of the weasel family and are about 1.2-1.5 m (4-5 ft)
in length and weigh 20-45 kg (45-100 lbs). Sea otters have webbed
hind feet and smaller front feet. They eat a variety of invertebrates
including crustaceans (crabs, lobsters and shrimps), bivalves
(clams, mussels and abalone) and echinoderms (sea urchins and
sea stars). They also eat octopus, squid and fish. Underneath each
front arm is a pouch of loose skin that temporarily stores food and
rocks collected during dives. Floating on their backs, sea otters
rinse and hammer open prey with a rock they keep in their pouch.
They are the only mammal (besides primates) known to use tools.
17
6.2 MARINE ALGAE / SEAWEED
CALIFORNIA SEA LION
California sea lions have a pair of small external ears. They swim
using their fore-flippers like oars while their hind flippers are not
used. On land, their hind flippers can be turned forward under body
and used for movement. There are about 160,000 California sea
lions and they are found off the coasts of California, Mexico and the
Galapagos islands. They eat fish and molluscs (e.g. octopus and
squid).
GREAT WHITE SHARK
The great white shark is considered a large and dangerous shark.
They spend much of their life in the open ocean but will move into
coastal waters seasonally to hunt for sea lions and seals. It has a
heavy body, large head, and pointed snout, with large triangular
teeth with serrated edges. Its body is slate blue or leaden grey
above and dirty white below. It can reach a length of 7.9 m (26 ft)
but is usually less than 4.9 m (16 ft). The great white shark is a
member of the Mackerel Shark family and was probably made
infamous through the movie “Jaws”.
18
6.2 MARINE ALGAE / SEAWEED
OCTOPUS
The octopus is a cephalopod (an unshelled mollusc) that inhabits
several different ocean habitats. Octopuses are characterized by
their eight arms (not tentacles) which usually have suction cups on
them. Unlike most other cephalopods, the majority of octopuses
have almost entirely soft bodies with no internal skeleton. They have
neither a protective outer shell (like the nautilus) nor any vestige of
an internal shell or bones, (like cuttlefish or squids). A beak, similar
in shape to a parrot's beak, is the only hard part of their body. As a
result, an octopus can squeeze between narrow crevices. This is
very useful when it is hiding from morays or other predators.
SEA ANEMONE
Sea anemones are simple animals (cnidarians) that are often
attached to the sea bottom. Sea anemones have cylindrical bodies
that are surrounded by upward-facing tentacles. The tentacles have
stinging cells on them which kill prey and move the food into a sea
anemone’s mouth. The mouth leads into the body cavity which
digests the food. A continuous current of water through the mouth
circulates through the body cavity and removes waste.
Sea
anemones are found in cold and warm waters. Many are colourful,
and large species can be 1 m (3 ft) in diameter.
19
6.2 MARINE ALGAE / SEAWEED
SEA STAR
Sea stars (or starfish) are soft-bodied marine animals with five arms.
Sea stars are echinoderms, a large group of invertebrates which
include sea urchins, sand dollars, sea cucumbers and brittle stars.
Sea stars typically live in the middle of a tidal range and can survive
short periods of exposure to air as the tide retreats.
SEA URCHIN
Sea urchins are echinoderms.
They are round, spiny and
herbivorous invertebrates that graze on algae and detritus from
grass beds and rocky areas. Many sea urchins have long, sharp
spines on their backs, which protect them from predators such as
fish, crabs, moray eels and sea otters. However, their underside is
often spineless and they are vulnerable to attack from that side if the
predator can turn the sea urchin over.
20
6.3 OCEAN LIFE
6.3 OCEAN LIFE
21
6.3 OCEAN LIFE
6.3 OCEAN LIFE
6.3.1 Horseshoe Crabs
DESCRIPTION
Horseshoe crabs are an ancient species of invertebrates related to
the trilobites. They are regarded as living fossils since they have
stayed unchanged for more than 350 million years. Horseshoe
crabs are not, in fact, true crabs (crustaceans) and are more closely
related to spiders & scorpions (arachnids).
CHARACTERISTICS
Horseshoe crabs have a hard chitin-based exoskeleton with 3
segments – prosoma (head), opisthosoma (abdomen) and telson
(tail). They have 10 eyes, 5 pairs of jointed, pincered, walking legs
and 1 pair of feeding pincers (chelicerae). They have light-blue,
copper-based blood and breathe through “book gills” (thin plates
located on abdomen).
SIZE
Males are 18-23 cm (7-9 in) across the prosoma and 33-41 cm (1316 in) in length (head to tip of tail). Females are typically 30% larger
than males and are 23-31 cm (9-12 in) across the prosoma & 41-51
cm (16-20 in) in length (head to tip of tail).
22
6.3 OCEAN LIFE
LIFESPAN
Horseshoe crabs take 8-10 years to reach adulthood and their
lifespan is 20-30 years.
DIET
Horseshoe crabs eat worms, mollusks and dead fish. They find prey
along the sea bed and use their chelicerae to find & push food into
their mouths.
REPRODUCTION
In winter, horseshoe crabs move offshore and hibernate half-buried
in ocean sediments. In spring, they move towards beaches to
reproduce. A male hooks onto a female using his first pair of
walking legs (“pedipalps”) & remains attached to her. The female
then scoops out a shallow nest in the sand and lays 3,000 to 20,000
small jade-green eggs about 20 cm (8 in) into the sand. The male
then fertilizes the eggs as she drags him over them. Young
horseshoe crabs hatch in about 1 month. The mating season lasts
from April through December.
DISTRIBUTION
Horseshoe crabs are found off the coasts of Japan, Hong Kong,
Indonesia, the eastern USA (e.g. ME, NY, NJ & DE) and the Gulf of
Mexico.
23
6.3 OCEAN LIFE
24
USES
Horseshoe crabs have several uses in medicine. An extract of horseshoe crab blood – Limulus
amoebocyte lysate (LAL) – is used to ensure biomedical products (e.g. vaccines) are free of bacterial
contamination. Horseshoe crab chitin is used in manufacturing chitin-coated suturing filament and
wound dressing for burn victims.
THREATS
Horseshoe crabs are threatened by shoreline development and habitat loss, pollution, their use as bait
by conch & eel fisheries, and for their blood and chitin by the biomedical industry.
SPECIES
Today, there are 4 species worldwide. Limulus polyphemus is found in the Northwest Atlantic Ocean,
the other three are found in the Far East.
INTERESTING FACTS
Have light-blue, copper-based blood (unlike humans, which have red, iron-based blood)
Very important animals from a human perspective as they have several uses in medicine
Host to numerous parasites – barnacles, blue mussels, slipper shells, bryozoans, & sponges
Although horseshoe crabs look formidable, they are harmless and do not use their pointed tail as a
weapon but only to right themselves when they are turned over.
Horseshoe crabs are not true crabs – actually quite different in spite of general resemblance
25
6.3 OCEAN LIFE
Horseshoe Crabs
True Crabs
No antennae
No mandibles
Multiple un-stalked eyes
Moult by walking forward out of their shell
Have antennae
1 pair of mandibles
Stalked eyes
True crabs back out of their shell when malting
12 legs (6 pairs) including 6 pairs of claws:
1st pair (chelicerae) – for feeding
2nd pair (pedipalps) – differentiate gender
Remaining pairs are walking legs
10 legs (5 pairs) including 1 pair of claws
REFERENCES & FURTHER READING
http://www.horseshoecrab.org/
All about the horseshoe crab: natural history, anatomy, conservation & current research
http://www.ocean.udel.edu/horseshoecrab/index.html
University of Delaware Sea Grant College Program
http://www.dnr.state.md.us/education/horseshoecrab/
Maryland Department of Natural Resources
6.3 OCEAN LIFE
6.3.2 Sturgeons
DESCRIPTION
 Large, primitive, bony fish
 Skeleton has large proportion of cartilage
 Head bony
 Long snout with a row of 4 barbels in front of mouth
 Mouth ventral and protrusible
 Adults have no teeth
 May have a spiracle above and behind eye
 1 dorsal fin set far back
 Large bony plates (“scutes”) on body
 Heterocercal caudal fin (upper lobe longer than lower lobe)
 Long lived – 50–100 years
 Can take many years to mature–6-25 years depending on species
SIZE
To 6.1 m (20 ft) and more than 1,134 kg (2,500 lbs)
SWIMMING
Swim with their caudal fin (tail) and form an “S” shape with their
body and tail
Isinglass – a gelatinous semi-transparent substance obtained by
cleaning and drying the swim bladders of the sturgeon, cod and
other fishes. It is used in the clarification of wines & beers and in
glues & adhesives.
26
6.3 OCEAN LIFE
27
SCALES
Five rows of large bony plates (“scutes”) on body;
(1 on back, 1 at middle of each side and 1 on each side of belly)
Scutes better developed in young, virtually disappear in old individuals
Skin between scute rows covered with smaller bony scales
TEETH
Adults are toothless
DIET
Barbels used to help detect bottom-dwelling prey
Slurp up prey with their protrusible mouth
Feed on bottom-dwelling organisms – worms, mollusks & crustaceans
BREEDING & REPRODUCTION
All sturgeons spawn in freshwater
Sturgeon eggs/roe are highly valued as “caviar”
Several species are anadromous (spending much of their life in the sea but moving to fresh water to
spawn)
DISTRIBUTION
Found in rivers, lakes, bays and estuaries
Northern hemisphere – North America, Europe, Russia (Caspian Sea, Black Sea), Asia
6.3 OCEAN LIFE
28
CAVIAR
“Caviar” refers to the processed, salted eggs/roe of certain species of fish, most notably the sturgeon.
Sturgeon caviar or true caviar is sold worldwide as a delicacy, and is usually eaten by itself or spread on
toast or blinis (small, yeast-raised Russian buckwheat pancakes). Sturgeon eggs are round and vary in
size from very small to pea-sized. Their colour can be off-white, gold, light grey, charcoal grey, or black.
Most of the world’s caviar today comes from sturgeons in the Caspian Sea, which is ringed by
Azerbaijan, Iran, Russia, Turkmenistan, and Kazakhstan. The rarest and most expensive are marketed
as Beluga, Ossetra, and Sevruga caviar, which come from the Great Sturgeon (Huso huso), Russian
Sturgeon (Acipenser gueldenstaedtii) and Stellate Sturgeon (Acipenser stellatus) respectively.
Interestingly, the U.S. also had a history in caviar production. For most of the 19th century, the U.S. was
the main producer of the world's caviar. Caviar was actually given away free with beer in saloons for the
same reason salty peanuts are given away today. By 1910, however, lake sturgeons were so overfished they were nearly extinct and American production was stopped. In 1925, the Caspian Sea
fisheries began the commercial production we know today. Today, American caviar is mainly farmed
and typically comes from the White Sturgeon (Acipenser transmontanus), Lake Sturgeon (Acipenser
fulvescens) and Shovelnose Sturgeon (Scaphiryhnchus platoryhnchus).
The market demand and commercial value of caviar has resulted in the serious decline in sturgeon
numbers worldwide, especially those from the Caspian Sea. Sturgeons take many years to attain
maturity and the female sturgeon is killed in the process of extracting the eggs. Thus, in spite of some
protection and alleviation of demand through sturgeon farming, most sturgeon species remain
threatened or endangered.
6.3 OCEAN LIFE
CLASSIFICATION
29
6.3 OCEAN LIFE
STURGEON SPECIES
1. ATLANTIC STURGEON–ACIPENSER OXYRHYNCHUS
Long snout, sharply V-shaped and upturned
Viscera pale
Labrador to Florida and N.E. Gulf of Mexico
Mostly in shallow waters of continental shelf
Enters larger rivers to spawn
Commercially important; seriously depleted
To 3.1 m (10 ft) in length
2. SHORTNOSE STURGEON–ACIPENSER BREVIROSTRUM
Short snout, not upturned at tip
Short barbels
Viscera blackish
New Brunswick to N.E. Florida
Mostly in river mouths, estuaries and bays but also enters open sea
Seriously depleted
To 1 m (40 in) in length
30
6.3 OCEAN LIFE
3. GREEN STURGEON–ACIPENSER MEDIROSTRIS
23-30 scutes in midside row
1-2 mid-dorsal scutes behind dorsal fin
4 barbels nearer mouth than snout tip
Grayish white to olive-green
Bottom grubbing
Often in brackish water
Japan to Northern Baja
To 2.1 m (7 ft) in length and 159 kg (350 lbs)
4. WHITE STURGEON–ACIPENSER TRANSMONTANUS
38-48 scutes in midside row
No mid-dorsal scute after the dorsal fin
4 barbels closer to snout tip than mouth
Grayish white
Spawns in spring in fresh water
Important commercially for flesh and eggs (caviar)
Mainly in fresh water; occasionally moves to ocean
Common in large rivers
Alaska to Northern Baja
To 3.1 m (10 ft) in length and 181 kg (400 lbs)
31
6.3 OCEAN LIFE
32
THREATS
 Pollution and environmental degradation
 Over-fishing – for eggs/roe, meat and swim bladders
CONSERVATION
 The World Conservation Union considers all but two of the world’s sturgeon and paddlefish species
globally threatened. Consumer demand for caviar and the collapse of Russian law enforcement in
certain areas have caused a boom in illegal poaching. Habitat destruction has also contributed to the
decline of these fish.
 IUCN classifies the Great/Beluga sturgeon (Huso huso) as Endangered. It is a protected species and
its trade is restricted under CITES. The U.S. Fish & Wildlife Service has also banned imports of beluga
caviar and other beluga sturgeon products from the Caspian Sea since October 7, 2005.
 The World Wildlife Fund suggests not buying Beluga, Ossetra or Sevruga caviar, or caviar from the
Caspian Sea region, which includes Russia, Kazakhstan, Turkmenistan, Azerbaijan and Iran.
 Sturgeon and/or paddlefish farming may become a viable means of sustainable commercial caviar
production. It is currently practiced in Spain, France, Uruguay and the U.S. (California).
 Dwindling sturgeon numbers has also resulted in the creation of caviar-quality roe alternatives from
other fishes, such as Paddlefish, Whitefish, Cod, and Salmon.
6.3 OCEAN LIFE
33
REFERENCES & FURTHER READING
http://www.caviaremptor.org/
"Caviar Emptor" strives to protect critically endangered beluga sturgeon and other threatened Caspian
Sea sturgeon species (source of most of the world's caviar).
http://www.fishbase.org
Excellent source of information about fishes
http://www.worldwildlife.org/trade/faqs_caviar.cfm
World Wildlife Fund information on caviar trade
6.3 OCEAN LIFE
6.3.3 Sea Otters
DESCRIPTION
Long, sleek, furred, streamlined marine mammals
Largest member of the weasel family; 1.2-1.5 m (4-5 ft) long and weigh 20-45 kg (45-100 lbs)
Webbed hind feet; smaller front feet; ears and nostrils close when underwater.
Dense, luxurious, dark-brown fur; only marine mammal with almost no insulating fat
SPECIES
One species, Enhydra lutris, and two sub-species:
 Enhydra lutris nerisis – Southern/Californian sea otter
 Enhydra lutris lutris – Northern/Alaskan sea otter
SIZE
Southern sea otters
Females 1.2 m (4 ft) in length & 20 kg (45 lbs) in weight
Males 1.5 m (5 ft) in length & 30 kg (65 lbs) in weight
Northern sea otters
Generally heavier and more robust; Males up to 45 kg (100 lbs)
34
6.3 OCEAN LIFE
35
FUR
Two layers; soft, warm, dense undercoat and outer coat of guard hairs
Densest fur of any mammal – 500,000-1,000,000 hairs per sq. inch
Groom fur with forepaws to keep the fur waterproof
Almost no layer of insulating fat
Oil spills cause the fur to lose its waterproofing capability causing the sea otter to get hypothermia and
usually killing it
“POUCH”
Under each foreleg and extending across the chest is loose skin which can act as a “pouch”. Sea otter
may carry up to 25 sea urchins and a number of clams or stones in this pouch depending on their size.
6.3 OCEAN LIFE
36
6.3 OCEAN LIFE
SENSES
Keen senses – smell, hearing and sight
Can see very well, both above and below water
TEETH
Powerful jaws for crushing
Compact molars with smooth cusps; canines are rounded and suited
for crushing shellfish
Look “cute and cuddly” but they are large carnivores – they can and
do bite!
LIFESPAN
Male: 10-15 years in the wild
Female: 15-20 years in the wild
GROOMING
May spend 11%-48% of daylight hours grooming
Extreme flexibility allows them to groom all parts of their body
DIVING
Dive to about 100 m (330 ft)
Sea otters can hold their breath for 5 minutes
Most dives are about 1-1½ minutes long
37
6.3 OCEAN LIFE
DIET
Carnivores (meat eaters)
Eat crustaceans (crabs, lobsters, shrimps), bi-valves (clams,
mussels, abalone), sea-urchins and snails
Also eat octopuses, squid, and fish
Hunt for prey in the ocean and on the sea floor
Use rocks to help crack open clams and abalone
High metabolism – eat 20%-30% of their body weight a day in the
wild. This would be equivalent to a 68 kg (150 lb) human eating 1423 kg (30-50 lbs) of food a day just to survive
BEHAVIOUR
Either solitary or in groups called rafts
Females avoid males outside breeding periods
Sea otters segregate into male and female areas
Diurnal – hunt, feed and groom during the day
Sleep and rest on their backs, usually anchored in kelp
Wrap themselves in mats of kelp to secure them from currents
Tool use – underneath each front arm is a pouch of skin used to
temporarily store food and rocks collected during extended dives to
the bottom. Floating on their backs, sea otters wash and hammer or
pry open prey with a favored rock they keep in their pouch. Only
mammal, besides primates, known to use tools.
38
6.3 OCEAN LIFE
BREEDING & REPRODUCTION
Polygynous – one male may mate with several females
Males reach sexual maturity at 5-6 years old
Females come into estrus at 4-6 years old
Births occur all year but peak in Jan-Mar and Aug-Oct
Females give birth to one pup after a gestation period of 6-8 months
Courtship is often very playful. Males and females swim and dive
together with the male twisting and doing corkscrews in the water.
The male will also swim face down and much more quickly than
usual.
Females may also have scars on their nose from the males’ habit of
holding the females muzzles in their jaws during copulation.
May be a period of delayed implantation during which the fertilized
egg lies dormant – allows birth to be timed to when food is more
plentiful or conditions are better.
PREDATORS
Generally only a few
Ocean:
Killer whales; some sharks (great white) & birds (bald eagle)
Land:
Bears and coyotes
39
6.3 OCEAN LIFE
INTERESTING FACTS
Bones can be pale violet from eating purple sea urchins and
absorbing a chemical called “polyhydronaphthoquinone” from the
sea urchin.
Fifth digit (“pinkie”) on the hind foot is the longest digit, unlike that of
any other mammal.
Uses a rock as an anvil and hammers shellfish onto the rock to
smash it open. Rare example of mammalian tool use.
Smallest marine mammal
Does not have blubber
Has little/no need to come onto land – all life functions can and are
usually taken care of in water (i.e. breeding, birthing, mating, eating,
resting, grooming, etc).
Considered to be a keystone species controlling the population of
several invertebrates, which would otherwise grow unchecked.
40
41
6.3 OCEAN LIFE
CLASSIFICATION
6.3 OCEAN LIFE
HABITAT
Shallow coastal waters of northern Pacific
Ocean.
RANGE
Live along rocky northern Pacific Ocean coasts,
bays and kelp beds. Historic range throughout
the northern Pacific Ocean from Baja, California
through Washington, British Columbia, and
Alaska to the Aleutian Chain, Kamchatka,
eastern Russia and northern Japan. Much
sparser distribution today due to over-hunting of
sea otters for their pelts.
POPULATION
2,500 southern sea otters off the coast of
California
27,500-52,500 northern sea otters in Alaska,
Canada and Washington.
15,000 in Russia
42
6.3 OCEAN LIFE
43
THE GREAT HUNT
Between the 17th and 19th centuries, Russia was heavily involved in the sable fur trade. Peter the Great
declared that Russia should have the monopoly in sable furs and that they should find new populations
of sable to hunt. The Russians conquered Kamchatka, at the eastern edge of Russia, where they
harvested sable and sea otter fur, and explored the northwestern Pacific looking for sea routes to North
America.
Vitus Bering, a Dane in the service of the Russian navy, was given the task of mapping the Arctic coast
from northern Russia to the Americas. Bering’s 1741 expedition to North America returned with 900 sea
otter pelts – enough to pay for the entire expedition and set what came to be known as the Great Hunt in
motion.
Subsequently, the Russians sent many ships to hunt sea otters, which depleted their populations in the
Commander and Aleutian Islands. By 1776, the Americans and Europeans were also hunting sea otters
and competing with one another for domination of the fur trade. By 1867, Alaska was almost completely
depleted of sea otters. It wasn't until 1911 that an international treaty was signed to stop the hunting of
sea otters and the Great Hunt was finally over.
By that time, however, so few sea otters remained, many assumed they would become extinct. Indeed,
all California sea otters were thought to be extinct into the 1900’s. In 1915, however, 32 sea otters were
discovered at Point Sur in California. So fragile was this remnant population that biologists kept it secret
from the public until the 1930's. This and other surviving groups would form the nucleus for the
restoration of the sea otters.
Since then, and under strict protection, both Northern and Southern sea otter populations have grown
considerably but in some areas, their numbers are still precariously low (hence the Southern sea otters’
“Threatened” status). Today, new challenges threaten the sea otter’s existence, including pollution and
habitat destruction.
6.3 OCEAN LIFE
44
THREATS
• Hunting – almost driven extinct in the past; protected today
• Oil spills & pollution
• Habitat loss
• Disease and medical problems
• Gill net entanglement
• Human-sea otter competition – sea otters can damage valuable abalone & shellfish farms
CONSERVATION
California (Southern) sea otters listed as “threatened” under the federal Endangered Species Act (ESA)
and are fully protected under California state law. Alaskan (Northern) sea otters are “endangered”. All
otters in the USA are protected under the US Marine Mammal Protection Act (MMPA). Canadian otters
are classed as “threatened” by the Committee on the Status of Endangered Wildlife in Canada
(COSEWIC).
Even though they are protected, some threats have no boundaries:
• Exxon Valdez spill in Prince William Sound, Alaska (1989) killed several thousand sea otters
• Sticky crude oil causes water-logging of the coat & the animal quickly chills in the cold water
• May also succumb to the toxic components in the oil itself
REFERENCES & FURTHER READING
http://www.marinemammalcenter.org/learning/education/teacher_resources/cleanseaotter.asp
http://en.wikipedia.org/wiki/sea_otter - sea otter species information, habitat, behavior, threats
6.4 ACTIVITIES
6.4 ACTIVITIES
45
46
6.4 ACTIVITIES
6.4 ACTIVITIES
6.4.1 Horseshoe Crabs
CORE ACTIVITY
(a) Colour the horseshoe crab olive and add the following labels to your picture:
Top View
 Head (prosoma)
 Eyes
 Eyes (second set)
 Flange
 Hinge
 Abdomen (opisthosoma)
 Spines
 Tail (telson)
Bottom View
 Mouth
 Flange
 Feeding pincers (chelicerae)
 Tail (telson)
 Walking legs
 Book Gills
 Anus
6.4 ACTIVITIES
47
48
6.4 ACTIVITIES
(b) What are some differences between a horseshoe crab and true crab?
Horseshoe Crabs
True Crabs
(c) What colour is horseshoe crab blood?
(d) If you have to pick up a horseshoe crab, where should you hold it?
49
6.4 ACTIVITIES
ANSWERS
(a) Colour the horseshoe crab olive and add the following labels to your picture:
Top View
 Head (prosoma)
 Eyes
 Eyes (second set)
 Flange
 Hinge
 Abdomen (opisthosoma)
 Spines
 Tail (telson)
Bottom View
 Mouth
 Flange
 Feeding pincers (chelicerae)
 Tail (telson)
 Walking legs
 Book Gills
 Anus
6.4 ACTIVITIES
50
51
6.4 ACTIVITIES
(b) What are some differences between a horseshoe crab and true crab?
Horseshoe Crabs
True Crabs
 No antennae
 No mandibles
 Multiple un-stalked eyes
 Molt by walking forward out of their shell
 Have antennae
 1 pair of mandibles
 Stalked eyes
 True crabs back out of their shell when molting
12 legs (6 pairs) including 6 pairs of claws:
 1st pair (chelicerae) – for feeding
 2nd pair (pedipalps) – differentiate gender
 Remaining pairs are walking legs
10 legs (5 pairs) including 1 pair of claws
(c) What colour is horseshoe crab blood?
Light-blue, copper-based blood (unlike humans, which have red, iron-based blood)
(d) If you have to pick up a horseshoe crab, where should you hold it?
From the flange at the front of the head as though you were holding a bicycle helmet – not by the tail as
you can snap it off!
6.4 ACTIVITIES
6.4.2 Sturgeons
CORE ACTIVITY
(a) Colour the sturgeon dark grey and add the
following labels to your picture:
 Scutes (plated “scales”)
 Pectoral Fin
 Caudal Fin (“tail”)
 Barbels (“whiskers”)
 Snout
 Eye
(b) What is caviar?
(c) Why are sturgeons endangered?
(d) Why is the gathering of caviar from sturgeons so detrimental to the population?
52
6.4 ACTIVITIES
ANSWERS
(a) Colour the sturgeon dark grey and add the
following labels to your picture:
 Scutes (plated “scales”)
 Pectoral Fin
 Caudal Fin (“tail”)
 Barbels (“whiskers”)
 Snout
 Eye
53
6.4 ACTIVITIES
54
(b) What is caviar?
“Caviar” refers to the processed, salted eggs/roe of certain species of fish, most notably the sturgeon.
Sturgeon caviar or true caviar is sold worldwide as a delicacy, and is usually eaten by itself or spread on
toast or blinis (small, yeast-raised Russian buckwheat pancakes). Sturgeon eggs are round and vary in
size from very small to pea-sized. Their colour can be off-white, gold, light grey, charcoal grey, or black.
(c) Why are sturgeons endangered?
• Pollution and environmental degradation
• Over-fishing – for eggs/roe, meat and swim bladders
(d) Why is the gathering of caviar from sturgeons so detrimental to the population?
There are at least three reasons:
1. Gathering caviar (eggs) removes the next generation of sturgeons.
2. The female sturgeon is killed in the process of extracting the eggs.
3. Sturgeons take many years to reach maturity and reproductive age
6.4 ACTIVITIES
6.4.3 Sea Otters
CORE ACTIVITY
(a)
Colour the Sea Otter dark brown and add the following labels to your picture:
• Eye
• Forepaw
• Skin/Fur
• Nostril
• Hindpaw
• Ear
• Tail
(b) Name some of the sea otters most unusual features
55
6.4 ACTIVITIES
56
6.4 ACTIVITIES
(c) Sea otters are found along the coast of the
North Pacific ocean. Label the map with the
following places:
• California (CA), USA
• Alaska (AK), USA
• Canada
• Kamchatka Peninsula
• Russia
• China
57
6.4 ACTIVITIES
ANSWERS
(a)
Colour the Sea Otter dark brown and add the following labels to your picture:
• Eye
• Forepaw
• Skin/Fur
• Nostril
• Hindpaw
• Ear
• Tail
(b) Name some of the sea otters most unusual features
• Bones can be pale violet from eating purple sea urchins
• Fifth digit (“pinkie”) on the hind foot is the longest digit, unlike that of any other mammal.
• Uses rocks as an anvil and hammers shellfish onto the rock to smash it open
• Smallest marine mammal
• Does not have blubber
• Densest fur of any mammal – 500,000-1,000,000 hairs per sq. inch
58
6.4 ACTIVITIES
59
6.4 ACTIVITIES
(c) Sea otters are found along the coast of the
North Pacific ocean. Label the map with the
following places:
• California (CA), USA
• Alaska (AK), USA
• Canada
• Kamchatka Peninsula
• Russia
• China
60