Download Chapter 13

INTERTIDAL COMMUNITIES
Part of Chapters:
2, 4, 5, 11, 13, 20
Study of Ecology

Environment: All of the living and non-living factors
of an area.
 biotic
factors: living factors (animals, plants, fungi, ect)
 abiotic factors: non-living factors (wind, temp, currents,
salinity, ect)


Habitat: a place where an organism lives
Niche: the role an organism plays in their
environment. No two species can have the exact
same niche.
Populations and Communities


Population : A group of the same species in a
specified area.
Community : Many different populations in a
specified area.
Populations and Communities

Population growth
 there
are many ways in which a population can increase
in size
 Birth
and immigration
 exponential
growth: drastic growth in a short period of
time.
 carrying
capacity: the amount of organisms a specific
area can support without running out or degrading
resources.
Populations and Communities

Distribution of marine communities
 pelagic
division: all the water in the oceans
 neritic
zone: water above the continental shelf.
 pelagic zone (oceanic zone): all the water pass the neritic
zone (covers the deep areas)



photic zone: where sunlight can penetrate and support
photosynthesis
disphotic zone: minimal sunlight can reach. Not enough for
photosynthesis
aphotic zone: no sunlight
 Plankton:
organisms that drift with currents
 Nekton: organisms that can swim against currents
Populations and Communities
Benthic division: The ground below the water in the oceans
Shelf zone: area that extends from high tide line to the continental
slope
Bathyal zone: Below the shelf zone
Abyssal zone: Below the Bathyal zone (the deep)
Hadal zone: Below the Abyssal zone. Deepest areas in the
oceans. Usually found in trenches.
Epifauna: Organisms that live on the sea bottom
Infauna: Organism that live in the sediment of the sea bottom
Characteristics of the Intertidal Zone

Daily fluctuations of the environment
 organisms
must tolerate radical changes in temperature,
salinity and moisture, and endure the crushing force of
waves

Inhabitants are most active during high tide, when
area is submerged
 water

provides food for filter feeders
As the tide retreats, organisms adjust to exposure to
air and sunlight
Environmental Factors Affect Organism
Distribution

Maintaining homeostasis (internal balance)
 Affected
by changes in external environment
 internal adjustments made to maintain a stable internal
environment
 homeostasis and the distribution of marine organisms
 Optimal
 Zone
range:
of stress:
 Zones
of intolerance:
Environmental Factors Affect Organism
Distribution

Physical environment
 sunlight
 Photosynthesis
 Vision
 Desiccation
 temperature
 Ectotherms:
 Endotherms:
Environmental Factors Affect Organism
Distribution
 Salinity:
 Solutes:
 Osmosis:

Isotonic:

Hypertonic:

Hypotonic:
Environmental Factors Affect Organism
Distribution
 metabolic
requirements
 nutrients
and limiting nutrients
 oxygen as a requirement for metabolism
 anaerobic and aerobic organisms
 Eutrophication:
 metabolic
 carbon
wastes
dioxide is a common byproduct of metabolism
Environmental Factors Affect Organism
Distribution

Biological environment
 Competition
interspecific:
 intraspecific:
 competitive exclusion:
 resource partitioning:

 predator-prey
 balance
relationships
of abundance of prey vs. predators
 keystone predators:
Tides

Why tides occur
 tides
result from the gravitational pull of the moon and
the sun
 though smaller, the moon is closer to earth, so its
gravitational pull is greater
 water moves toward the moon, forming a bulge at the
point directly under it
 the centrifugal force opposite the moon forms another
bulge
 areas of low water form between bulges
Tides

Spring and neap tides
 during
spring tides, the times of highest and lowest
tides, the earth, moon and sun are in a line, combining
the pull of the sun and moon
 when the sun and moon are at right angles, the sun’s
pull offsets the moon’s, resulting in neap tides, which
have the smallest change between high and low tide
Tides
Types of Tides:
 Diurnal:
 Semidiurnal:
 mixed
 Tidal
semidiurnal:
range:
Waves

Wave formation
 Wave:
 Generating
force:
 most
common = wind
 also geological events, falling objects, ships
 Restoring
force:
Waves
 deepwater
and shallow-water waves
 deepwater
waves:
 breakers
 deepwater
waves become shallow-water waves when they
move into shallow water
 surf zone:
 breakers
form when the wave’s bottom slows but its crest
continues at a faster speed


plungers form when the beach slope is steep
spillers are found on flatter beaches
Waves
 tsunamis
 seismic
sea waves are formed by earthquakes
 tsunamis have long wavelengths, long periods and low
height
 compression of the wave’s energy into a smaller volume
upon approaching a coast or island causes a dramatic
increase in height
Intertidal Zonation


Zonation—separation of organisms into prominent
horizontal bands defined by color or distribution of
organisms
As tide retreats...
 upper
regions exposed to air, changing temperatures,
solar radiation, dissication
 lower regions exposed only a short time before tide
returns to cover them
Intertidal Zonation
 Supralittoral
(maritime) zone:
 Supralittoral
fringe (splash zone):
Intetidal Zonation

Zone system (continued)
 Midlittoral
zone:
 Infralittoral
 Subtidal
fringe:
(infralittoral) zone:
Intertidal Fishes

Resident species
 typically
have special adaptations for surviving harsh
intertidal conditions
 small
size; absent, reduced or firmly attached scales;
compressed/elongate or depressed body shape; absent or
reduced swim bladder; greater body density
 tolerant of temperature and salinity changes
 some intertidal fish can leave the water to feed

Temporary inhabitants
 tidal,
seasonal and accidental visitors
Rocky Shores and Sandy Shores

Rocky shores are found on the west coast from Alaska
south and on the east coast cape cod north.


Have all 5 intertidal zones. Organisms attach to rocky surfaces
and create a visiable zoning.
Sandy Shores are found mainly on the east coast,
cape cod south and along gulf coast.

Only have 3 zones (Supralittoral zone, Midlittoral, Infralittoral
zone). Does not show zonation because most organisms are found
in the sand.
Role of Waves and Sediments


Sediment particle size influences the beach’s nature,
porosity of sediments, ability of animals to burrow
Wave action influences sediment type:
 heavy
wave action = coarse sediments
 little wave action = fine sediments

Beach slope results from interaction of waves,
sediment particle size, and relationship of swash
and backwash
Role of Waves and Sediments
 Swash:
 Backwash:

Types of beaches:
 dissipative
 usually
flat with fine sediment
 reflective
 usually
beach:
beach:
steep with course sediment
Role of Waves and Sediments

On all sandy beaches, a cushion of water separates
the grains of sand below a certain depth
 especially
true on beaches with fine sand where
capillary action is greatest

Fine sand beaches have a greater abundance of
organisms
 greater
water retention
 sediment is more suitable for burrowing
Meiofauna


Meiofauna:
Characteristics of the meiofauna




invertebrates from many phyla
generally elongated with few lateral projections
many are armored to protect them from being crushed by moving
sand grains
include predators, herbivores, suspension feeders and detrivores
Linnaeus and Biological Classification

Binomial system of naming
 binomial
nomenclature:
 introduced
by Swedish botanist Karl von Linné (Carolus
Linnaeus) in 1750
 e.g. Chaetodon longirostris (long-nose butterflyfish) and
Chaetodon ocellata (spotfin butterflyfish) are both in the
same genus
Linnaeus and Biological Classification

Taxonomic categories
 Early
schemes of classification
 all
living things were classified into 1 of 2 kingdoms,
Animalia and Plantae, until 1960s
 Modern
classification
 major
categories: domain, kingdom, phylum, class, order,
family, genus, and species


Domains: Archaea, Eubacteria, Eukarya
Kingdoms: Eukarya contains 4 kingdoms, Fungi, Plantae and
Animalia, Protista
 protists—eukaryotic organisms that do not fit the definition
of animal, plant or fungus
Marine Reptiles


Reptiles adapted for success on land, then used the
same characteristics to return to the sea and gain
success there as well
Modern-day reptiles include:
 crocodilians
 turtles
 lizards
 snakes
Amniotic Egg

An amniotic egg is covered by a protective shell
and contains:
 Amnion:
 yolk
sac:
 Allantois:
 Chorion:

Copulatory organs allow efficient internal
fertilization
Physiological Adaptations

Advanced circulatory system in which circulation
through the lungs is nearly completely separate
from circulation through the rest of the body
 more


efficient method of supplying oxygen
Kidneys are efficient in eliminating wastes while
conserving water
Skin covered with scales and lacking glands
decreases water loss
Marine Crocodiles





Best adapted to the marine environment is the Asian
saltwater crocodile (Crocodylus porosus)
Large animals (up to 6 m long)
Feed mainly on fishes
Drink salt water and eliminate excess salt through
salt glands on their tongues
Lives along the shore, where it nests
Sea Turtles

Adaptations to life at sea
 protective
shells that are fused to the skeleton and fill in
the spaces between the vertebrae and ribs protect their
bodies
 outer
layer of shell composed of keratin
 inner layer composed of bone
 Carapace:
 Plastron:
 leatherback
turtle lacks shell and has a thick hide
containing small bony plates
Sea Turtles

Adaptations to life at sea (continued)
 shell
is flattened, streamlined,d reduced in size and
weight, for buoyancy/swimming
 large fatty deposits beneath the skin and light, spongy
bones add buoyancy
 front limbs are modified into large flippers
 back limbs are paddle shaped and used for steering
and digging nests
Sea Turtles

Behavior
 generally
solitary, don’t interact
 remain submerged while at sea; breathe air but can
stay under water for as long as 3 hours
 alternate between feeding and resting during the day
 sleep on the bottom under rocks or coral
Sea Turtles

Feeding and nutrition
 have
a beak-like structure instead of teeth
 green sea turtle is the only herbivore
 leatherback sea turtles eat jellyfish
 pharynx
is lined with sharp spines to hold slippery prey
 digestive system adapted to withstand stings
 large
amounts of salt consumed with food and water
are eliminated as concentrated tears through salt
glands above the eyes
Sea Turtles

Reproduction
 courtship
– males court females before mating; males
may compete for a female, or 1 female may mate with
several males
 nesting – females dig shallow pits on the beach, usually
at night, and bury eggs
 development and hatching
 temperature
determines development time and sex ratio
 hatchlings rush for the safety of the sea after hatching
Sea Turtles

Turtle migrations
 females
migrate from feeding grounds to the beaches
where they were born to nest
 green sea turtles feed on grasses in warm, shallow
continental waters, but breed on remote islands
 some
breed on a 2- or 3-year cycle
 method
for navigation over long distances is unknown
Sea Turtles

Sea turtles in danger
 beach
erosion
 artificial lighting near nesting beaches
 sea turtles are killed when trapped in fishing nests,
especially those used for shrimpers
 turtle
exclusion devices can reduce turtle mortality by as
much as 95% when used for shrimp nets
 turtles
are hunted by humans for meat, eggs, leather
and shells
Marine Iguana


The marine iguana of the Galápagos Islands off
Ecuador is the only marine lizard
Most are black, but some are mottled red and
black
 dark
coloration is thought to allow more absorption of
heat energy
 raising body temperature allows them to swim and
feed in cold Pacific waters
Marine Iguana

Feeding and nutrition
 herbivores
with a short, heavy snout for grazing on
dense mats of seaweed
 swallow small stones to reduce buoyancy for feeding
under water
 excess salt from consumed seawater is extracted and
excreted by specialized tear and nasal glands
Marine Iguana

Behaviors
 good
swimmers, using lateral undulations of the body
and tail
 each male occupies a small territory on the rocks,
usually with 1 or 2 females
 intruders or challengers are attacked when they enter
the male’s territory
 fights
between male iguanas rarely result in serious injury
Sea Snakes

Adaptations to life in the sea
 scales
are absent or greatly reduced for streamlining
 tail is laterally compressed into a paddle
 nostrils are higher on the head
 valves
in the nostrils prevent water from entering when the
snake is submerged
 single
lung reaches to the tail, and trachea is modified
to act as an accessory lung by absorbing oxygen
Sea Snakes

Adaptations to life in the sea (cont.)
 can
exchange gases through the skin while under water
 can lower metabolic rate to use less O2

Feeding and nutrition
 eat
mainly fish and eels, sometimes eggs
 most ambush prey and strike with venomous fangs
 can swallow prey more than twice their diameter
Sea Snakes

Sea snakes and humans
 sea
snake venom is toxic to humans
 being timid, sea snakes rarely bite humans; people eat
them in Japan
Seabirds




250 of 8,500 bird species are adapted to live near
or in the sea
Seabirds feed in the sea
Some spend months away from land, but all must
return to land to breed
Types of seabirds:
shorebirds
 gulls and their relatives
 pelicans and their relatives
 tubenoses
 penguins

Adaptations for Flight






Homeothermic:
Feathers aid in flight and insulate
High rate of metabolism to supply energy for active
flight/nervous system
Strong muscles, quick responses, great deal of
coordination
Advanced respiratory system with 4-chambered
heart
Keen senses
Adapting to Life in the Sea

Large amounts of salt are consumed with food and
salt water
 salt
glands above the eyes produce tears to remove
excess salt
 these tears have twice the salt concentration of
seawater
Shorebirds


Waders with long legs and thin, sharp bills used to
feed on intertidal organisms
Oystercatchers, curlews & turnstones
 oystercatchers
use long, blunt, vertically-flattened
orange bills to slice through adductor muscles of bivalve
molluscs
 long-billed curlew uses its bill like a forceps to extract
shellfish from burrows
Shorebirds
 heavyset
turnstones use slightly upturned bills as
crowbars to turn over stones, sticks and beach debris in
search of food
Shorebirds

Avocets, stilts, and sandpipers
 avocets
and stilts have very long legs, elongated necks,
and slender bodies
 avocets wade through shallow water, moving a
partially opened beak from side to side through the
water, to feed
 stilts probe the mud for small animals (e.g. insects,
crustaceans) with their bills
 sociable sandpipers feed on small crustaceans and
molluscs as the surf retreats
Shorebirds

Herons (e.g. egrets and bitterns)
 most
stand still and wait for prey to come in range to
feed
 some stalk prey or stir up the bottom to frighten prey
into motion so it can be caught
Gulls and their Relatives





Gulls have webbed feet and oil glands to
waterproof their feathers
They are not true ocean-going birds, and do not
stray far from land
Have enormous appetites
Are not very selective feeders
Relatives of gulls include terns, skuas, jaeger birds,
skimmers and alcids
Gulls and their Relatives

Gulls
 herring
gulls are the most widespread, and are vocal,
gray and white, and travel in large groups
 feeding
 noisy,
aggressive, efficient predators and scavengers
 may drop prey with hard shells on rocks or parking lots to
break the shell open
 highly successful at finding food and surviving
Gulls and their Relatives

Gulls (continued)
 nesting
 highly
gregarious; gather in large colonies
 not picky about nesting sites or materials
 both sexes assist in incubating 2-3 eggs
 chicks hatch in 3-4 weeks, and remain in the nest until almost
fully grown, camouflaged by speckled down
 chicks are vulnerable to predation by other animals and by
other gulls
Gulls and their Relatives

Terns
small, graceful birds with brightly-colored and delicatelysculpted bills, forked tails
 hunt by plunging into the water for fish and invertebrates;
will steal food
 usually gregarious nesters


Skuas and jaegers
very aggressive omnivores and predators
 “hawks” or “vultures” of the sea
 jaegers will pursue other birds to steal their prey

Gulls and their Relatives

Skimmers (scissorbills)
 small
birds with pupils that are vertical slits and a
flexible lower jaw protruding much farther than the
upper bill
 fly over water and use the lower bill to create ripples
at the water’s surface that attract fish
 fish are then collected by flying along the same path
over the water a second time
Gulls and their Relatives

Alcids (e.g. auks, puffins, murres)
 look
like penguins but are related to gulls
 convergent
 ecological
 major
evolution:
equivalents:
difference is that alcids can fly
Pelicans and their Relatives




E.g., gannets, boobies, cormorants, darters,
frigatebirds, tropicbirds
Have webs between all 4 toes
Upper mandible is hooked in pelicans, cormorants
and frigatebirds
Many are brightly colored, or have head
adornments
Pelicans and their Relatives

Pelicans
 large
birds preferring warm latitudes and estuary,
coastal and inland waters
 require a large fish population to support colonies of
large birds
 feed just under the water’s surface using gular pouches
as nets
 gular
pouch—a sac of skin that hangs between the flexible
bones of the bird’s lower mandible
Pelicans and their Relatives

Boobies
 dive
into the sea from 18-30 m up to fish
 species lay differing numbers of eggs; this is thought to
reflect the reliability of the food supply around where
they nest

Cormorants
 swim
along the surface scanning for fish, then plunge
deep to pursue them
 lacking oil glands, they must periodically dry their
wings in order to fly
Pelicans and their Relatives

Cormorants (continued)
 most
are strong fliers, but the Galápagos Island species
is flightless
 guano cormorant of the coast of Peru valued for its
guano (bird manure)

Frigatebirds
 lightweight
body and near 2 m wingspan
 lacking oil glands, they feed by skimming with their bills
 pursue/attack other birds to steal prey
Tubenoses




E.g. petrels, albatrosses, shearwaters
Have obvious tubular nostrils on their beaks which
join with large nasal cavities within the head
Nasal glands secrete concentrated salt solution
Stomachs contain a large gland that produces a
yellow oil composed of liquefied fat and vitamin A,
used for feeding hatchlings and defense
Tubenoses

Albatrosses
 gliders
with wings nearly 3.5 m long
 most live in the Southern Hemisphere where winds circle
the earth without encountering land
 usually come to land only to breed
 courtship displays precede mating
 1 egg is incubated by both parents on a volcanoshaped nest, and the young are fed on stomach oil,
then regurgitated fish
Penguins


Bird most adapted to marine lifestyle
Awkward on land, but swift swimmers
 flap
their wings to swim
 torpedo-shaped bodies are streamlined
 flat, webbed feet are used for steering
 leap from the water to breathe


Eat fishes, squid and krill
Eaten by leopard seals and killer whales
Penguins

Reproduction in Antarctic species
 adelie
penguins lay eggs in summer; emperor penguins
in mid-winter
 female emperor penguin lays 1 egg, which the male
incubates for 2 months while she visits her feeding
grounds
 egg
sits on his feet, covered by a fold of skin
 male can feed the chick a secretion from his crop if it
hatches before female’s return
 crop—a digestive organ that stores food before it is
processed
Penguins
 female
returns with food in her crop for the chick, and
male can feed
 both parents help to feed the chick once it reaches 6
weeks
 by summer, the chick can feed itself, and is ready to
enter the sea