Lecture 15 Fish Behavior
1. Reproduction
2. Migration
3. Symbiosis
4. Predation Behavioral ecology Selection keeps a watchful eye… …organisms behave in ways that maximize their fitness Parental care
Some form of defense or manipulation of eggs or young
• 90 families include species that provide care
• 31% Biparental care, 69% uniparental care • most common caregiver male
• External fertilizers 89%, Internal fertilizers 11% • External: 90% male care • Internal: 86% female care
• Male care likely evolved to insure no other males fertilize eggs… Hermaphrodites Why change sex?
Increased fitness • change sex when, at a given size, the reproductive success of the other gender becomes higher
• females limited by number of gametes produced, males limited by number of matings • sex change theory predicts it best to be male when small and female when large
However, sex change also depends on ecologies of individual species… Protogynous Hermaphrodites
- almost universal in wrasses (Labridae) Female
Juvenile
Male Embiotoca jacksoni, E. lateralis Black surfperch, Striped surfperch 40
35 Embiotoca jacksoni
30
25
20
15
10
5
0 1 2 3 4 5 6 7 8 9 10 11 12
35 Embiotoca lateralis 30
25 Number of offspring Number
20
15
10
5
0 1 2 3 4 5 6 7 8 9 10 11 12 Female Fixed Action Patterns Fixed Action Patterns: stereotypical innate behavior. The organism will carry it out almost no matter what, even if it doesn’t seem appropriate.
Three-spined stickleback Gasterosteus aculeatus Fixed Action Patterns Male three spined stickleback: attacks other males with red bellies – attacks anything red Learning & Cognition
• Change in behavior based on experience – e.g., Habituation, Imprinting, Conditioning: Pavlov
• Cognition – The connection between nervous system function and behavior – Consciousness and awareness Use of a rock as an anvil Coyer, 1995
Halichoeres garnoti Yellowhead wrasse Tool Use in Fishes
Orange-dotted tuskfish Choerodon anchorago Learning in Archerfish Migration
• Spatial orientation and mapping – Migration: Piloting, orientation (directional headings), navigation (relative location) – The role of learning in migration – (magnetite, light, etc..) Daily Migration The deep scattering layer Migration
complex migration patterns Migration Spawning migration Tagging Great White Sharks http://topp.org/features/fab_flight_white_shark
A white shark tagged with both acoustic (front) and pop-up satellite (rear) tags. The acoustic tag is detected when the shark swims within 250 m of a listening station, while the pop-up satellite tag records information about location, temperature and depth – and relays it to the laboratory when the tag releases itself from the shark. Weng et al. 2007 White Sharks by the Season
Weng et al. 2007 Symbiosis
• Fish - Fish
• Fish - Invertebrates
• Fish - Other vertebrates Symbiosis Fish-Fish Trumpetfish / herbivores Symbiosis Fish-Fish Alternative Strategies Symbiosis Fish- Inverts
Clownfishes / Anemones Pearlfishes and their hosts… Goby and Ghost Shrimp Symbiosis Fish-other verts Predation
Two different categories of predators have evolved
• Speed to overtake prey
• Minimal aerobic effort – deceptive tactics The Need for Speed
Over take prey with speed Predation lie and wait – sometimes involves deception