Transcript Limnology Lecture 15? Outline • What is ethology? • Influence of aquatic environment • Basic behaviors: – Movement – Feeding – Escaping • More complex behaviors.

Limnology
Lecture 15?
Outline
• What is ethology?
• Influence of aquatic environment
• Basic behaviors:
– Movement
– Feeding
– Escaping
• More complex behaviors
Likens 1992
Ethology
ethos = character
logia = the study of
The scientific study of animal behavior, in the
context of anatomy, physiology, ecology,
neurobiology and phylogenetic history
Ethology
Fathers of Modern Ethology
1973 Nobel Prize in Physiology or Medicine
“for their discoveries concerning organization
and elicitation of individual and social
behaviour patterns".
Four Categories of
Ethology Questions:
• Causation
• Ontogeny
• Function
• Evolutionary History
Aquatic Environments
• More stable than terrestrial
• Aquatic organisms seldom exposed to
dessication
• Oxygen is a limiting factor
• Light can be a limiting factor
• Unique matrix: less gravity, challenges to
movement
Simple Behaviors in Aquatic Systems
• Swimming and escape behavior
• Feeding behavior
• Reproductive/mating behaviors
Swimming and Escape Behaviors
• Strong link between size and form on one
hand and size and locomotion on the other.
Ratio between viscous and inertial forces
determines optimal swimming behavior.
Taxis
=guided movement towards or away from a
stimulus.
Ex: phototaxis (light), aerotaxis (oxygen),
anemotaxis (wind), barotaxis (pressure),
magnetotaxis (magnetic field), rheotaxis (fluid
flow), thermotaxis (temperature), thigmotaxis
(physical contact), chemotaxis (chemicals)…
Feeding Preferences and Behavior
• Protozoans and
animals are
heterotrophic
• Energy through
consumption
• Simplest feeding
behavior= engulfing
(i.e. amoeba)
Functional Feeding Groups
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Predator
Omnivore
Collector (filtering or gathering)
Scraper/grazer
Shredder
Piercer
Functional Feeding Groups
• Predator
Functional Feeding Groups
• Omnivore
Functional Feeding Groups
• Collector (filtering or gathering)
=consume fine pieces of organic material
Filtering collector
Gathering collector
Functional Feeding Groups
• Scraper/Grazer
Functional Feeding Groups
• Shredder
Functional Feeding Groups
• Piercer
Habitat and Behavior Designations
Detail the functionality of the organism.
• Clinger
• Climber
• Sprawler
• Burrower
• Swimmer
• Diver
Protista
(K. Protista, NOT Animalia. Evidence of basic
behaviors)
• Swimming behavior simple, forward or
reverse. Move with cilium.
• Escape response: Change direction
Protista
(K. Protista, NOT Animalia. Evidence of basic
behaviors)
• Swimming behavior: simple, forward or
reverse. Move with cilium.
• Escape response: Change direction
• Feeding behavior: many phagotrophic.
Ciliates have cilia for capturing food complex
mouth regions.
Rotifers, Annelids, Arthropods
The small invertebrates. Common members of
zooplankton.
Rotifers
• Swim and capture food using the cilia on their
head. Some sessile.
• Pelagic forms (e.g. Keratella) can increase
swimming speed in response to a predator.
• Sessile forms build tubes to defend against
predators. Short-range escape response.
• Feeding behavior: some filter, some catch prey
with elongated trophi.
Annelida
• Except leeches, swim rarely and poorly.
• Usually burrow.
• Escape response: sudden contraction, change
of direction.
• Feeding behavior: most ingest bacteria and
detritus.
• Leeches: attach to host.
Branchiopods
• Movement diverse: swim smoothly, row or
hop, swim in short jerks, creep, or may glue
back to substrate
• Many species show tropisms or taxes
• Some with swarming behavior
• Well-developed escape response – rapid
change in motion and/or looping motion
• Bosmina with “dead-man’s response”
Copepods
• Typically fast and agile.
• Escape response in some copepods: jumps.
Copepods
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Typically fast and agile.
Escape response in some copepods: jumps.
Show strong tropisms to light and currents
Feeding: young (nauplii) eat small particles.
Adults feed by filtration, grasping, or scraping.
Most omnivorous.
Malacostracans
• Can walk, swim, and escape rapidly.
• Tend to be omnivorous (e.g. crayfish), which
can lead to problems of over-consumption.
Insects
• Aquatic larvae: variety of creeping, walking or
swimming behaviors. (Table 4.6 in book)
• Escape behaviors: primarily fast swimming in
opposite direction
• Feeding habits: variety. Aquatic insects tend
to be omnivorous. Shredders, scrapers,
collectors, predators, piercers.
Larger Organisms:
Mollusks, Fishes, Other Vertebrates
Include “charismatic aquatic megafauna”. Often
of direct and significant economic importance.
Mollusks
• Most able to move in habitat. Snails most
active. Bivalves move using muscular foot.
• Snails have shown an escape response to
specific chemical signals.
• Freshwater snails are ALL herbivorous.
Bivalves are filter feeders, eat fine particles.
Zebra Mussels
Fishes
• Strong relationship between feeding
preferences, habitat, and feeding behavior
• Often use vision to find prey. SO predation
often restricted to daylight hours. Other
sensory systems: taste, lateral line, electric
field.
• Most fishes exhibit saltatory search behavior
Fishes: Specialist feeders
• Planktivores
• Piscivores
• Detritivores
• Herbivores
• Benthivores
• Omnivores
Other Verts
Classes Amphibia, Reptilia, Aves, Mammalia.
• Tetrapod verts- relatively large animals.
Allows for fast and powerful movement
• Many tend to be at the top of the food chain.
• Predaceous aquatic species include adult
amphibians, all aquatic snakes, and most
birds.
Complex Behaviors
• Communication
• Schooling
• Mating
• Sociality
• Learning
• Altruism
• Defense
• Fighting