Fish Function and Ecology

Question 1

Ectothermy vs Endothermy, etc.

Answer 1

Ectothermy: body is not kept warm by internal heat
Endothermy: body is warmed by internal heat

“True” endothermy: temperature is regulated and maintained in a constant range
Non-thermoregulating endothermy: internal temp is always a couple deg. warmer than environment (not constant temp)

Question 2

Most fishes’ internal temperature depends on water temperature

Answer 2

Almost all fishes are ectothermic - consequence of having gills
- Tuna and a few sharks: non-thermoregulating endotherms

Question 3

Opah (Lampridiformes) is the only truly endothermic fish

Answer 3

Fat tissue on and counter-current heat exchange in gill arch allow opah to maintain body temp

Question 4

Cichlids (Ovalentaria) are an important model for studying evolution

Answer 4

Continental drift (they’re in South America and Africa)
Fresh water in Percomorpha, adaptive radiation

Question 5

Stickleback are used by multiple researchers at UofC

Answer 5

They have repeatedly invaded freshwater system from marine systems

Question 6

Many reef fishes make up the most derived groups in the Actinopterygian phylogeny

Answer 6

Interest to humans:
- Functional morphology
- Aquarium trade
- Fisheries (primarily in tropics)
- Habitat loss due to bleaching

Question 7

Fish functional morphology - how structure supports the function

Answer 7

• Position and size of head structures supports various feeding modes
• Eye and mouth position relate to foraging location (high eyes = eating above it)
• Head dorsal-ventral depth relates to diet (skinny head = fish eating fishes, tall head = plankton eating)
• Gape width relates to diet (how big mouth opens determines size of prey that is edible)

Question 8

Head positioning relative to prey also affects capture success

Answer 8

Suction is most powerful right next to mouth, protrusion sets up success
- May also be stealthy by rotating head as start feeding (seahorse)

Question 9

Studying fish functional morphology

Answer 9

Preserved specimens at natural history museums provide a wealth of morphological data
- Evolutionary approach: combo with phylogenetic tree to model processes
- Ecological approach: combo with habitat and abundance surveys
- Physical and computational models of swimming get at questions that are hard to study in real fishes
- Live fish swimming experiments

Question 10

What do we do with fish videos?

Answer 10

• Track body and fin movement patterns
• Calculate swimming forces
• Track particles -> water movement
• Compare parts of body and across species