Animals of the Pelagic Environment

Staying above the ocean floor o Gas containers Shells - rigid gas containers ex. celphalopods

Swim Bladders Internal organ to maintain buoyancy. Internal organ to maintain buoyancy. Expands or contracts ( add or removes gas) a.Gas exchange through blood to control height in water column

o Floating heterotrophs (Zooplankton) - surface 1. Microscopic zooplankton – primary consumers, herbivores or omnivores. a. Radiolarians – single celled, silica shells, intricate ornamentation to ↑ surface area so they don’t sink.

b. Foraminifera – single celled, calcium carbonate shells c. Copepods – shrimp-like crustaceans, largest biomass of plankton, important link in many marine food webs.

2. Macroscopic - seen with “unaided eye” a. Krill – crustacean, resemble mini shrimp or large copepods, over 1500 species. Abundant near Antarctica, critical link in food web.

b. Cnidarians - soft bodies, tentacles armed with stinging cells (nematocysts) 1). Hydrozoans 2). Scyphozoans (jellyfish)

c. Tunicates – barrel-shaped with openings at each end. Most are pelagic, usually transparent. Benthic tunicates Pelagic tunicates

d. Ctenophores – gelatinous, transparent, cilia e. Chaetognaths (arrow worms) – dart-like, voracious feeders

© 2011 Pearson Education, Inc. Swimming Organisms Fish, squids, sea turtles, marine mammals Fish, squids, sea turtles, marine mammals Swim by trapping water and expelling it, e.g., some squid Swim by trapping water and expelling it, e.g., some squid Swim by curving body from front to back Swim by curving body from front to back

© 2011 Pearson Education, Inc. Swimming Motion and General Fish Features

© 2011 Pearson Education, Inc. Fin Designs in Fish Paired vertical fins as stabilizers Paired vertical fins as stabilizers Paired pelvic fins and pectoral fins for “steering” and balance Paired pelvic fins and pectoral fins for “steering” and balance Tail fin (caudal) for thrust Tail fin (caudal) for thrust

© 2011 Pearson Education, Inc. Fin Designs in Fish Rounded caudal fins Rounded caudal fins –Flexible –Maneuver at slow speeds Truncate fins and forked fins Truncate fins and forked fins –Useful for both maneuvering and thrust

© 2011 Pearson Education, Inc. Fin Designs in Fish Lunate fins Lunate fins –Rigid, little maneuverability – Efficient propulsion for fast swimmers Heterocercal fins Heterocercal fins –Asymmetrical, –Lift for buoyancy (shark) ins.htm

© 2011 Pearson Education, Inc. Adaptations for Finding Prey Mobility Mobility Lungers wait for prey and pounce (grouper). Lungers wait for prey and pounce (grouper). –Mainly white muscle tissue Cruisers actively seek prey (tuna). Cruisers actively seek prey (tuna). –Mostly red muscle tissue

© 2011 Pearson Education, Inc. Lungers and Cruisers

© 2011 Pearson Education, Inc. Adaptations for Finding Prey Swimming speed Swimming speed Speed generally proportional to size Speed generally proportional to size Can move very fast for short time (mainly to avoid predation) Can move very fast for short time (mainly to avoid predation)

© 2011 Pearson Education, Inc. Cold-Blooded vs. Warm-Blooded Most fish are cold-blooded – poikilothermic Most fish are cold-blooded – poikilothermic –Bodies same temperature as environment –Not fast swimmers Some are warm-blooded – homeothermic Some are warm-blooded – homeothermic –Found in warmer environments –Helps them capture prey –Faster, stronger – Tuna and Mackeral Sharks

© 2011 Pearson Education, Inc. Adaptations of Deep-Water Nekton Mainly fish that consume detritus or each other Mainly fish that consume detritus or each other Lack of abundant food Lack of abundant food Bioluminescence Bioluminescence –photophores Large, sensitive eyes Large, sensitive eyes Large sharp teeth Large sharp teeth Expandable bodies Expandable bodies Hinged jaws Hinged jaws Counterillumination Counterillumination

© 2011 Pearson Education, Inc. Adaptations to Avoid Predation Schooling Schooling –Safety in numbers –School may appear as single larger unit –Schooling maneuvers confuse predator

© 2011 Pearson Education, Inc. Adaptations to Avoid Predation Symbiosis – two or more organisms mutually benefit from association Symbiosis – two or more organisms mutually benefit from association Commensalism – less dominant organism benefits without harming host Commensalism – less dominant organism benefits without harming host

© 2011 Pearson Education, Inc. Adaptations to Avoid Predation Mutualism – both organisms benefit Mutualism – both organisms benefit –Example: clown fish and anemone Parasitism – parasite benefits at expense of host Parasitism – parasite benefits at expense of host

© 2011 Pearson Education, Inc. Adaptations to Avoid Predation Speed Speed Poisons Poisons Mimicry Mimicry Transparency Transparency Camouflage Camouflage

II. Marine Mammals A. Carnivora 1. Sea Otters a. Lack layer of blubber, but have extremely dense fur. b. Hunted to the brink of extinction in 1800’s c. Eat various shellfish and crustaceans – use rocks to break open shells. d. Commonly inhabit kelp beds 2. Polar Bears a. massive webbed paws = excellent swimmers Kelp Forest QT Video

b. Thick fur, each hair is hollow (insulation) c. Large teeth and sharp claws d. Diet – mainly seals 3. Walruses a. Large bodies b. Tusks – both male and female, used for territory fight- ing, hauling out, and stabbing prey

4. Seals – aka true seals or earless seals a. Lack prominent ear flaps b. Smaller, less prominent front flippers c. Prominent claws on foreflippers d. Different hip structure, can not move their rear flippers underneath their bodies. e. Do not move well on land, slither like a caterpillar. f. Propel through water using back and forth motion of their rear flippers. Seal QT Video

B. Sirenia 1. Manatees – coastal areas of Atlantic (tropical) a. Diet – vegetarian shallow water grasses b. Compete with humans for space c. endangered 2. Dugongs – tropical regions of Indian Ocean and Western Pacific a. Diet – same as manatees b. Compete - same c. endangered

C. Cetacea 1. Characteristics a. Elongated skulls b. Blowholes on top of skull c. Very few hairs d. Fluke – horizontal tail fin used for propulsion 2. Modifications – to ↑ speed a. Streamline bodies b. Specialized skin structures that ↓ pressure difference to reduce drag and turbulence 3. Modifications - for deep diving a. Specialized structures to use O 2 efficiently b. Ability to resist nitrogen narcosis 4. Suborder Odontoceti – toothed whales a. Difference between dolphins and porpoises

1). Porpoises are smaller and have a more stout body shape 2). Porpoises have blunt snout, dolphins longer 3). Porpoises have small- er more triangular (or no) dorsal fin. Dolphin – sickle-shaped = falcate 4.) Porpoises have blunt or flat teeth. Dolphin are conical

*Killer whales have conical teeth and are put in the dolphin family. b. Characteristics 1). prominent teeth – hold and orient fish and squid 2). Form complex, long-lived social groups 3). 1 external nasal opening (blowhole) 4). Best developed sound ability *sperm whales – most vocal 5). Echolocation 6.) Intelligent - ? a). Communicate with each other using sound b). Large brain sized relative to body size

c). Highly convoluted brain – characteristic shared and considered highly intelligent d). Some dolphins have assisted drowning humans in the wild. e). Dolphins have been trained Sperm whaleKiller whale

Pilot whale Narwhals Bottlenose Whale Beluga

5. Suborder Mysticeti – baleen whales a. Worlds largest – blue, finback and humpback Humpback Blue Whale WS

b. Only bottom feeder – grey whale c. Larger than odontocetes – difference in food source d. Baleen – hangs from upper jaw, made of keratin. Fill mouth with water & prey then force water between baleen trapping their prey.

e. 3 Families 1). Gray Whales – short, coarse baleen, no dorsal fin a). Migration – 22,000 km round trip journey every year. Feed in cold ↑ latitudes water, breed and give birth in warm tropical waters of Baja, California. b). Endangered but removed in 1993 > 20,000. NA Gray Whales – extinct, Japan - extinct Gray Whale Migration Video, Reading and WS

2). Rorqual Whales – short baleen a). Balaenopterids – long slender bodies, small sickle-shaped fins and smooth-edged flukes. Minke Whale Bryde’s Whale Sei Whale Fin Whale

Blue Whale

b). Megapterids - humpback, robust bodies, long flippers, flukes with uneven trailing edges, tiny dorsal fins & tubercles on head. Humpback Whales

3). Right Whales – long fine baleen, broad triangular flukes, no dorsal fins a). Most threatened with extinction b). Right and bowhead whales Right Whale Bowhead Whale