Download Ch. 15 Marine Animals Lecture Notes Page

LECTURE NOTES:
OCEANOGRAPHY (MARSC 100),
SNYDER, L.
CH. 15 Marine Animals
Earth’s Early Atmosphere contained little O2 (mostly: CO2, nitrogen, water vapor)
Oxygen Revolution:
~2 BYA (Billion years ago) photosynthetic autotrophs produced O2

 By ~900-700 MYA (million years ago), Enough O2 was produced to support
Animals
 Ozone layer also developed: Oxygen rising up from the troposphere & into the
stratosphere form Ozone (O3) when exposed to increased ultraviolet radiation.
o Ozone blocks out harmful UV sun from reaching the troposphere where we
all live.
The Invertebrates
90% of all living & fossil animals
Lack a rigid skeleton for muscle attachment
Soft bodies, many with hard covering
33 Phyla
Phylum: group of organisms with common architecture, complexity, evolution
Phylum Porifera (Sponges)
Most primitive animals (asymmetrical)
Benthic, sessile (attached, don’t move)
Reefs, rocks, sandy bottom, & on other organisms
Suspension feeders: strain plankton, organic debris from water
Sponges Body: simple or complex bag w/ many holes
 Water & food (dissolved nutrients, plankton) enters central cavity through holes
where food is digested. Excess water is expelled out the top of the sponge (“bag”).
o Collar cells (with tail-like flagella) aid this process by whipping water &
food into sponge
 Body (Bag) held rigid by small imbedded spicules (skeletal fragments)
Phylum Cnidaria
Sea anemones, coral, sea jellies
Radial symmetry (wheel)
2 forms:
medusae (free-swimming upside-down bag)
Ex: Sea jellies (jellyfish)
polyp (sessile, right-side up bags)
Ex: Anemones (often solitary), Coral (individual polyps live in colonial
groups
Cnidarians are Carnivores:
Prey on small fish & zooplankton
Nematocysts: Special organelles inside cnidoblast cells
Function like harpoons (sticky or armed with strong toxins)
Found on feeding tentacles
Coral Polyp
 One opening/exit for food & waste (Bottle gut)
 Zooxanthellae: symbiotic algae live in tissues
o Zooxan. Provide coral with: O2, proper pH, carbohydrates (glucose from
photosynthesis)
o In return, Zooxan. Receive from coral: CO2, nutrients, substrate &
protection
 Coral polyps Secrete a hard calcium carbonate skeleton (colony) that individual
polyps live in (like an apartment complex)
Worm Phyla
 Several distinct Phyla & classes
 Bilateral symmetry (left & right side mirror images)
 Selected Phyla Examples:
o Platyhelminthes (flatworms): Free-living scavengers & predators, many
very colorful
o Nematoda (roundworms): Often parasitic (fish, marine mamals)
o Annelida (segmented worms): Some mobile, some predators, many
immobile
 EX: Sedentary Tubeworms: build stony tubes for protection of soft
body that lives inside (often colonial)
 EX: Feather duster worm (tube worm) filter feeds on plankton &
dissolved nutrients with a colorful, feathery appendage
Phylum Mollusca
Several distinct classes:
Snails, clams, squid
Bilateral Symmetry
Heads & developed nervous system
Tube digestive tract (mouth & anus)
Class Gastropoda (Snails & slugs): “Belly-foots” (walk on belly with a muscular foot)
 Many with Calcium carbonate shell (snails, limpets)
 Some shell-less (Sea hare, nudibranch)
 Mostly herbivores (sharp tongue called a radula used to graze on algae)
Class Cephalopoda (squid, octopus, nautilus): “Head-foots” – head, foot, tentacles
 Most “shell-less” except nautilus & squid has an internal shell remnant called a pen
that is a slim, long, plastic-like rod that provides some support to the squid.
 Predators
 Suction cups on tentacles & arms aid in movement, prey acquisition, & feeding
 Move by creeping (octopus) or jet propulsion (squid & nautilus)
Class Bivalvia:
“Two-door (shell)”
Clams, oysters, mussels, scallops
Suspension (filter) feeders – filter plankton & dissolved nutrients from water
Some have siphon (tube): collects water & expells waste (clams)
Mussels: byssal threads hold to rock
Phylum Echinodermata:
“Spiny skin”, marine only
 Sea stars, brittle stars, sand dollars, sea urchins, & sea cucumbers
 5-sided radial symmetry (like a wheel or pie)
 Water-vascular system for movement & feeding via water pressure
o Water that enters the body is distributed by muscular contractions
o Water taken in from outside is circulated through canals & allows for
movement of tube feet
 Skeleton (not cucumbers) made of calcite plates
 Sea stars (carnivores): Have external digestion!
o Stomach comes out of their mouth so they can digest food outside of their
bodies (insert stomach into a mussel)
Phylum Arthropoda: Most numerous animals [mostly terrestrial (on land) - Class Insecta]
 Many marine (Class Crustacea):
 Copepods, krill, lobsters, shrimp, crabs, & barnacles
 Soft, segmented body & legs covered by exoskeleton
 Exoskeleton (hard, outside skeleton) is often molted (shed) & re-grown to allow for
growth
Higher Animals: The Chordates
Phylum Chordata – have a “spinal cord” at some stage of life
All chordate embryos have:
1.
Notochord: flexible rod for support (95% replace w/ vertebral column)
2.
Dorsal, Hollow Nerve cord: Develops into central nervous system
3.
Gill Slits: Gas Exchange (filter feeding for early chordates)
4.
Postanal tail
Invertebrate Chordates:

Urochordates (Tunicates):
o Notochord & tail absorbed in adult form: No more swimming, become
Sessile (immobile), sac-like filter-feeders

Cephalochordates (Lancelets)
o Retains notochord
o Lacks vertebrae
o Filter feed with their gill slits as adults
Vertebrate Chordates:
column)
have notochord, nerve cord, gill slits AND backbone (vertebral





Protects nerve (spinal) cord
Endoskeleton (inside skeleton): made of Bone, cartilage, or both
Bilateral symmetry
Complex Brain
Fishes are the most successful vertebrate – most numerous
Fishes: Most species & individuals of all vertebrates
 60% are marine
 Most ectothermic (cold-blooded): cannot regulate own body temp. = body same
temp. as external environment
 Have Gills (gas exchange) & fins (movement)
 3 classes: Agnanthans, Chondrichthyes, Osteichthyes
Class Agnantha: Lampreys & hagfishes
 Most primitive of fishes
 Feed by suction (round, muscular mouth & rows of teeth)
 Cylindrical body (like eel, snake)
 Cartilagenous skeletons
 Lack paired fins & scales
Ex: Lamprey: attach to other fish & suck their blood
Ex. Hagfish: eats dead & dying fish, bore into fish & eat from the inside out
Class Chondrichthyes: Cartilagenous Fish
 Sharks, skates, rays, chimeras
 Cartilage skeleton
 Alive for ~280 million years w/ little change
 Movable jaws with teeth
 Paired fins
Skates & Rays:
 Flattened bodies
 Wing-like pectoral fins, fused with head
 Gill slits on underside, eyes on top of head
 Often Live on bottom

Skates: Lack whip-like tail & stinger, lay eggs: "horns" secure capsule in algae

Rays:
o
o
o
some with stingers (stingrays)
Venomous spines w/ serrated barbs
Sting for defense
Some lack stingers:
 Guitarfish: Spines, but no stinger
 Electric rays: shock their prey
 Manta Rays: Pelagic (open water) swimmers (at surface)
 Eat Plankton!


Large: Pacific Manta up to 25 ft.
Sharks
o Fast swimming, predatory
o Most swim continuously (or drown): force water over gills (oily liver
helps buoyancy)
o Some rest on bottom (nurse, horn sharks)
o Internal fertilization, some live birth, some lay eggs
o Tiny, tooth-like scales (denticles) on skin
o Rows of teeth constantly replaced
Why do sharks have a bad reputation?
 375 shark species: only 30 reported to ever attack a human
 Only ~12 potentially dangerous if encountered, including:
o White (Carcharodon carcharias), Bull (Carcharhinus leucas), Tiger
(Galeocerdo cuvier)
 80% harmless (including horn, swell, leopard, bamboo, smoothound, basking, &
whale sharks (Whale & basking sharks eat plankton)
Worldwide Avg: 50-70 shark attacks/year
 Increased in recent decades due to:
o INCREASED Human population (6.5 billion) – 1 billion people prior to 1850
o Increased Use of ocean for recreation
 BUT, Fatalities have DECREASED substantially
o Due to Education, medicine
Humans kill ~ 1 million sharks for every human killed by a shark
 You’re 30 times more likely to be killed by lightning than a shark!
 Sharks are killed for a variety of reasons:
o Meat & fins, skin (leather), liver (vitamin oil), Sport, Fear, caught in fishing
nets (bycatch)
o Few killed are eaten Or just their fins are eaten (Shark Fin Soup)
 Finning (used to collect fins for shark fin soup): Sharks are caught alive,
their fins are cut off & then the rest of the shark is thrown back into the
sea to slowly bleed to death.
 An Enormous number of sharks are killed for shark fin soup
Unprovoked White Shark Attacks: 1874-2004 (130 years!)
Territory
Total
Fatal
Last
Attacks
Fatal
2004
World
212
61
2004
West
80
7
USA
2004
Australia
37
26
California (White Shark Attacks): 2004: 6 Attacks ( 1 Fatal)
World Shark Attacks 1990-2004: Florida: 40%, Calif: 4.3% (most are isolated around
Monterrey & San Francisco = “Red Triangle”)
Why Do Sharks Sometimes Attack Humans?
1.
Misidentification
 Diver & surfer silhouettes resemble pinnipeds (seals & sea lions), which are the
preferred prey of sharks (rich in blubber & fat)
2.
Sharks strike unfamiliar objects to test for food potential
 Decide a prey's palatability while in its mouth
 Prefer prey rich in energy (fat): marine mammals
 Spit out energy-poor prey (not fatty): Humans
Avoiding Shark Attacks
 Stay in groups (sharks attack individuals)
 Don’t go too far from shore (away from help)
 Sharks are most active & have sensory advantage at twilight & night
 Avoid water if bleeding (sharks can smell blood)
 Avoid areas used by: marine mammals, fisherman, bait fish, feeding seabirds
(sharks are likely to be hunting in these areas)
Why Should We Protect Sharks?
 Apex predators (top of the food chain): control prey populations & maintain
ecological balance
 Crucial part of complex food web:
o Feed on fish, shellfish & mammals
o Sick & dying
o Larger animals (whales, seals, tuna) that have few predators
 If removed, ecosystem balance is altered
o If shark numbers decrease, population sizes of seals & sea lions increase,
which causes fish populations to decrease because there are too many
seal/sea lions.
o This ultimately will decrease the fish availability for other species including
humans (results in crashes of commercial fisheries – no fish dinner for you)
Class Osteichthyes (Bony fish)
 Skeleton at least partially made of bone
 98% of all fishes (> 50% marine)
 ~75–100 new species described each year
 Most have scales protected by mucus
 Operculum: bony plates that cover & protect gills
 2 sub-classes:
1.
Coelacanths & Lungfishes
2.
Ray Fins
Order Teleost (Ray Fins)
 Most vertebrates are fish in the order Teleost
 90% of all fish
 Neutral Bouyancy (swim bladder)
 Great camouflage
 Movable fins = controlled swimmers
 Incredible diversity & adaptability to different habitats
Fish Problems: Living in Seawater
1.
Water is 1000X more dense (heavy) & 100X more viscous (thick) than air
 Water’s resistance to flow causes:
o Drag (resistance to movement)
o Turbulence around swimmer (large fish)
 Both slow fish down
 Minimize by streamlining (bullet shape)
o Retractable fins that can tuck close to body in fast fish (tuna)
2.



5% denser than sea water (bone, muscle)
Must maintain bouyancy or sink
Strenuous to swim constantly
Swim bladder: gas-filled sac in abdomen to adjust buoyancy (Gas lighter than H2O)
 Picks up oxygen & nitrogen from blood or mouth
 Rise or sink by regulating amount of gas in bladder
3.
Gas exchange in water (O2 in & CO2 out)
Fish take in oxygen dissolved (DO) in water
There is a lower percentage of oxygen in water than in air
But, many Active fish (tuna) are better at extracting oxygen than terrestrial (land) animals:
Tuna Extract 85% DO in water (25% Air breathers)
Oxygen Extraction by Fish Gills
Countercurrent flow: water & blood flow in opposite directions
a.
Water enters mouth
b.
Passes over gills
c.
O2 flows into gills to blood, CO2 flows out of blood to gills
d.
CO2 & water out of gills
4.
Regulate salts (Osmoregulate)
Osmosis: movement of water from areas of high to low concentration
Body fluids: High water, low salt concentration compared to seawater
Results in water moving out of fish by osmosis (leads to dehydration & a build up of salts
in fish tissues)
To counteract this: Fish drink seawater, but excrete salts by special salt glands in the gills
& produce concentrated urine (recycle water through kidneys)
5.
Feeding & avoiding predation, competition



o
Most of ocean is dark
Fish have many well-developed senses:
o Well developed sight & hearing
o Lateral Line System = can detect movement & vibrations in water
 Small canals with receptors (connect to brain)
 Detect predators or prey
 Used by schooling fish to move in unison (provides camouflage b/c
many fish together look like one big fish = less likely to be attacked
by a predator)
 Ampullae of Lorenzini (sharks detect electrical fields of prey)
Fish have many ways to camouflage:
o Cryptic Coloration: blend in with background (sediment, algae, coral reef)
Countershading: Dark back (blends in w/ dark seafloor), Light belly (blends
in with light from sea surface)
o
Extremely common in free-swimming pelagic (open ocean) species
o Schooling (safety in numbers)
Tetrapods (Four-limbed vertebrates):
Class Reptilia (Sea Turtles, Sea Snakes, Marine Crocodile, Marine Iguana)
Land reptiles that returned to the Sea
Ectothermic (cold-blooded = body temp. same as external environment)
Breathe air with lungs, scales
Salt glands excrete excess salt
Most live in tropics or subtropics
Marine Iguana (1 species)
Endemic to Galapagos Islands (found nowhere else)
Eat marine algae
Long claws to hang on rocks
Wide tail acts like rudder
Sea Turtles (7 living species)
Live up to 80 yrs.
Warm & temperate water
Food: sea jellies, algae, crustaceans, molluscs
Threatened with extinction (5 of 7 species listed as endangered):
 Hunted (meat, shell, eggs); beach & nest destruction; tangled in nets; pollution; eat
plastic (mistake for their sea jelly prey)
o Avoid using plastic (ask for paper bags at grocery store) & be sure to recycle it
Sea Turtles Lay Eggs on Beaches (~70-170 eggs at a time)
 Hatched Babies Must Return over beach to the Sea
Class Aves (birds)
Evolved from dinosaurs (160 MYA)
Scaly legs, claws
Endotherms, Feathers
Flyers have light, hollow bones
All lay eggs on land
Salt excreting glands
3% of birds are seabirds
Marine birds include shorebirds
Gulls & Terns
Coastal
Successful fishers & scavengers
Terns are plunge divers
Shorebirds
Estuaries, shore
Eat fish & marine invertebrates
Most migrate from northern (summer) breeding grounds
TO
Southern, winter grounds
 Rest & winter in estuaries
 Pacific Flyway:

Shorebirds (& many other marine bird species) breed & nest in Alaska & NW
Canada during summer (warm, sunlight = a lot of vegetation & insects to eat)

Fly along Pacific Coast in fall to S. Calif, Mexico, & S. America where they spend
winter in estuaries
Penguins & Allies (Puffins, auklets, murres)
Great Swimmers
Penguins can’t fly & live in Southern Hemisphere only
Pelicans & Allies (Cormorants)
Throat pouch
Brown Pelican: Endangered species in Calif. (DDT)
White Pelican: Cooperative feeders
Cormorants: Deep diving birds (Great divers & swimmers, but Bad flyers), Great
Solid bones & oily feathers help them to dive, but make flying difficult
Tubenoses (Albatross, shearwater, jaeger)
Come on land only to breed, rest of time spent at sea
Albatross: Great flyers Horrible at landing
Jaegers are kleptoparasites = steal food on wing from other birds
Marine Mammals
Marine Mammal Characteristics
1. Large Brain
2. Internal fertilization
3. Live young (Viviparous)
4. Body hair
5. Few young (raise until mature)
6. Embryo nourished via a placenta
7. Young fed milk (mammary glands)
8. Tetrapods (2 pairs of limbs)
9. Lungs for respiration (breathe air)
10. Endothermic (warm blooded): maintain a high internal body temp by metabolic
processes
Marine Mammal Taxonomic Classification:
 Class Mammalia:
o 4 Orders (Pinnepedia, Carnivora, Sirenia, Cetacea)
o 2 Suborders (Order Cetacea: suborders: Odontoceti, Mysticeti)
 Evolved from land mammals
 Returned to sea 50 MYA
Marine Mammal Adaptations
 Diving Adaptations
1. Respiratory system collects/retains O2:
2. Excellent O2 storage in blood (High Myoglobin + Hemoglobin concentration
O2 carrying pigments in blood)
3. Bradycardia- slows heart rate while underwater to conserve O2
4. Collapse lungs when diving (decreases Nitrogen gas dissolving blood = “the
bends”)

Temperature Maintenance:
1.
Thick blubber (except otters), some have thick fur
2.
Few blood capillaries at surface
3.
Shunt blood away from extremities (Pinnipeds)
4.
Huge blood volume for body size

Osmotic regulation (No salt glands):
1.
Concentrated urine (water recycled through kidneys)
2.
Don’t drink seawater, skin impervious, prey supplies freshwater
Order Pinnepedia (Pinnepeds): Seals, sea lions, walruses
 Predators, have Blubber, Breed on land
 Seal & sea lion identification:
o Sea Lions: earflaps, large, rotational front flippers, long neck, walk well on
land
o Seals: no earflap (just hole for ear), short front flipper, short neck, walk
poorly on land (sausages)
 Walruses: Eat benthic invetebrates, use whiskers as feelers
Order Carnivora (Polar Bears, sea otters)
Not closely related (polar bears related to land bears – grizzly, sea otters are mustelids =
related to weasels, skunks, etc,)
Polar Bears (Marine bear)
 Semi-aquatic (will swim out to sea up to ~ 40 miles)
 Rely on sea ice to hunt for prey (seals, small whales, etc.)
 Thick fur & blubber
 Threatened by Global Warming: melted sea ice will inhibit hunting
Sea Otters
 Range: Pacific Coast from Baja California to Alaska/Russia (especially around
Aleutian & Russian islands)
 Hunted to near extinction for fur
 Keep warm with:
o Dense fur (densest of all animals), little blubber
o Air between fur & skin
o High metabolic rate: Eat 15-20 lbs/day (25-30% of body wt.)
 Use tools (rocks, shells) to eat urchin, shellfish
Order Sirenia (Manatees, Dugongs, Steller’s Sea Cow – extinct)
 Warm, shallow, tropical seas (Manatee – Caribbean, Dugong – SE Asia)
 Herbivores (seagrasses, algae)
 Severely Endangered
 Boat propellers kill & injure
 Elephant are closest relatives
Order Cetacea: Whales, Dolphins, Porpoises
Suborder: Mysticeti (Baleen Whales)
 Blue, finback, gray humpback, right, minke, sei
 2 Blowholes
 Baleen = fibrous protein (keratin):
o Filters plankton from water or invertebrates from mud
o Tongue pushes food to throat, excess water/mud spit out
o Strains water: plankton, krill, sm. Fish, benthic inverts.
 Communicate with low frequency sounds (songs). Humpback over very long
distances

Gray Whale Migration
o ~ 6,000 mi. each way (Dec-April)
o calving & breeding (Baja, Mexico)
TO
o Summer feeding (Alaska & Siberia)
o East. Pacific Gray’s Pop. is increasing (numbers have increased from ~1000
to ~25,000)
o West. Pacific Pop. till endangered
Suborder: Odontoceti (Toothed Whales)
 Sperm, pilot, orca, dolphin, porpoise, narwhale, beluga
 1 Blowhole
 Peg Teeth
 Social (live in family pods)
 Echolocation: Produce sounds (clicks) with melon, sounds bounce of prey, objects
in sea, & sound wave is received in their jaw, then transferred via nervous system to
brain (interprets image)

Allows them to “See” 3D picture of environment

Detect food (type & size of prey)

May stun prey
Are Orcas Speciating?
 Residents & transients (two distinct groups)
o Live in same area (sympatric)
o Differ in: morphology (outer body structure – fins) , behavior, social habits,
foraging
o On genetic path towards speciation
 Reproductively isolated
o Studies based on Pacific Northwest
Major Differences
 Residents
o Piscivorous (eat fish)
o Cooperative feeding
o Travel in large pods (5-50)
o Use a lot of Vocalization
 Transients
o Eat marine mammals
o Feed alone or with only slight cooperation (Mom may help offspring until they
learn)
o Travel in small pods (1-7) – 3 is most common
o Little vocalization