Animals of the Pelagic Environment. Making a living--adaptations Staying Above the Seafloor. Adaptations

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Allan Sims
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Temperature Group Behavior Reproduction Schooling Migrations Adaptations To make

food to eat and how to obtain it 3) how to avoid predators 4) where, how, when to

1 Animals of the Pelagic Environment Making a living--adaptations Staying Above the Seafloor Eating Gas Containers Floaters Swimmers (nekton) Mobility Speed Temperature Group Behavior Reproduction Schooling Migrations Adaptations To make a living organisms must meet the following challenges: 1) where to live 2) what food to eat and how to obtain it 3) how to avoid predators 4) where, how, when to reproduce They are strongly influenced by the usual factors: temperature, density, etc. 1

2 Planktonic forms: Zooplankton Zooplankton are the animals of the plankton. They cannot swim against the currents. Every major phylum of the animal kingdom is represented Their size ranges from micrometers (protists) to tens of meters ("Jellies") Zooplankton Continued... Zooplankton typically grow fast, and this is very dependent on the food supply Distribution - Zooplankton typically occur in patches with a high density of organisms, but they may accumulate along a particular depth e.g., the pycnocline, DSL 2

3 Common Zooplankton Copepods and euphausids (krill) Foraminifera and radiolarians Transparent forms or "Jellies". There are the so-called true Jellies (Cnidaria) and the Ctenophores, or comb-jellies Salps and tunicates True Nekton This group can regulate both their horizontal and vertical position, and include: Fish Molluscs (squid, cuttlefish, nautilus) Reptiles Marine Birds Marine Mammals (>50% of time at sea) 3

Buoyancy 4 groups, based on vertical positioning: Size-Independent This

small they don t sink very rapidly Adaptations are size- and

Swimmers Buoyancy: Gas Containers Use a gas chamber to regulate depth

4 Buoyancy 4 groups, based on vertical positioning: Size-Independent This includes the smallest organisms Primarily the smaller zooplankton So small they don t sink very rapidly Adaptations are size- and shape-related Gas Containers Floaters (no hard parts)-neutrally buoyant Swimmers Buoyancy: Gas Containers Use a gas chamber to regulate depth (buoyancy)--similar to a diver s BCD Limited to about 500 m depth (the crush depth) for nautilus 4

rapidly or slowly adjusted Buoyancy: Floaters Contain very little hard tissue Includes:

5 Buoyancy: Fish Bladders A special case of gas containers, as most fish swim instead NOT found in fish that swim all the time such as tuna Below about 7000 m, the gas is replaced by fat Can be rapidly or slowly adjusted Buoyancy: Floaters Contain very little hard tissue Includes: Coelenterates Siphonophores Scyphazoans Tunicates Ctenophores Chaetognaths (usually placed in zooplankton group) 5

(stingers) Coelenterates-->Scyphazoans True jellyfish Don t contain a floatbag Uses

6 Coelenterates-->Siphonophores Bodies are more than 95% water Use a pneumatophore for buoyancy Colonial organism, with specialized individuals Includes nematocysts (stingers) Coelenterates-->Scyphazoans True jellyfish Don t contain a floatbag Uses muscular contraction of the bell to provide movement Capable of explosive growth by asexual budding 6

Tunicates Also called sea squirts, salps Are

material to depth Ctenophores Also called comb

7 Tunicates Also called sea squirts, salps Are chordates, but don t have a spine Use jet propulsion Can grow up to 40% per day in size! Can be important for export of organic material to depth Ctenophores Also called comb jellies, sea gooseberries Always pelagic, marine Carnivorous 7

8 Chaetognaths Also called arrow worms very important carnivores, intermediate step between small zooplankton and fish 8

Nekton (true swimmers) Squid Fishes Marine

htm Adaptations for Feeding Mobility and

9 Nekton (true swimmers) Squid Fishes Marine Mammals All of these groups expend more energy to maintain buoyancy first-video-of-a-giant-squid.htm Adaptations for Feeding Mobility and Speed are largely dependent on 3 factors: Length:Width (barracuda vs. sunfish) Caudal Fin morphology Red vs. white muscle mass 9

cold-water fishes that use antifreeze These glycoproteins bind to

10 Body Temperature Tuna are an example of countercurrent heat exchange systems Body Temperature The opposite extreme are cold-water fishes that use antifreeze These glycoproteins bind to small ice crystals in the cell, keeping them from forming bigger crystals 10

Class Mammalia Evolved from land back to sea Vestigial hind legs! Characteristics of marine mammals: 1. Warm-blooded 2. Breathe air 3. Have hair (or fur) 4. Birth to live young 5.

11 Class Mammalia Evolved from land back to sea Vestigial hind legs! Characteristics of marine mammals: 1. Warm-blooded 2. Breathe air 3. Have hair (or fur) 4. Birth to live young 5. Females have mammary glands that produce milk 6. Long life expectancy 7. Intelligent!!! Class Mammalia 3 Orders Carnivora [sea otters, polar bears, pinnipeds (seals, sea lions, walruses)] Sirenia (manatees and dugongs) Cetacea (whales, dolphins, porpoises) 11

12 Order carnivora Order Sirenia (Manatees and Dugongs) n Sirenian characteristics: n Large body size n Sparse hair all over body n Herbivores n n (need to be in coastal waters) Endangered! 12

Sirenians of the world Sea Cow discovered 1741, made extinct in 1768 http://www.savethemanatee.org/sirenian.

13 Sirenians of the world Sea Cow discovered 1741, made extinct in Order Cetacea (two suborders) Suborder Odontoceti (toothed whales) Echolocate (send sound through water) Killer whale, sperm whale, dolphins, porpoises Suborder Mysticeti (baleen whales) Have rows of baleen plates instead of teeth Finback whale, humpback whale, gray whale Blue whale: the largest animal ever (100 ft) About the size of a Boeing 737, but heavier 13

Marine Mammal Adaptations Marine Mammals: spend more than 50% of the time at sea Cetaceans (obviously) Pinnipeds Sea Otters Sirenians (manatees, dugongs, Stellar sea cow [extinct]) Polar Bears

14 Marine Mammal Adaptations Marine Mammals: spend more than 50% of the time at sea Cetaceans (obviously) Pinnipeds Sea Otters Sirenians (manatees, dugongs, Stellar sea cow [extinct]) Polar Bears Breathing Deep diving mammals have evolved to reduce oxygen consumption by: Increasing blood volume, capacity gliding as they dive Shutting off unnecessary organs during dives Developing flexible ribs No nitrogen narcosis 14

Behavioral Adaptations Schooling: found in over 2000 species of fishes Reduce the predator-prey encounter rate Less likely

15 Polar Bears Don t really have algae growing in their fur--at least not naturally Are so well insulated, that if photographed with infrared film, the only thing that shows up is its breath Have webbed rear feet and water-resistant coats Behavioral Adaptations Schooling: found in over 2000 species of fishes Reduce the predator-prey encounter rate Less likely to eat any given individual May appear as a single organism Confusing to predators Can be reproduced using simple rules on a computer 15

16 Behavior: Abduction Some organisms borrow another one to enhance survival Behavior: Migration 16

17 Fig. 1. Transoceanic migration of a white shark from South Africa to northwestern Australia and possible first leg of a second transoceanic-migrating shark. R Bonfil et al. Science 2005;310: Published by AAAS 17

ZOOPLANKTON. Zooplankton: 2. Crustaceans Copepods. Diverse -- protozoans and others

ZOOPLANKTON. Zooplankton: 2. Crustaceans Copepods. Diverse -- protozoans and others ZOOPLANKTON Diverse -- protozoans and others Nutrition modes: Herbivores (graze on phytoplankton) Carnivores (predators) Radiolaria Foraminifera Zooplankton: 1. Protozoans: Foraminifera and Radiolarians