Feeding morphology

Question 1

Factors that affect morphology of feeding (4)

Answer 1

• Jaw protrusion
• Pharyngeal Jaws
• Dentition
• Mouth position

Question 2

• Diet in many fish can be predicted by _____

Answer 2

body shape, mouth position and jaw shape, and dentition

Question 3

what is thought to be key innovation in the fish evolutionary tree

Answer 3

Jaw protrusion

Question 4

Jaw protrusion is most common in which kind of fish?

Answer 4

most common in higher
Teleost:
- cichlids,
- clupeids
- percids
- centrarchids
- labrids

Question 5

jaw protrusion

Answer 5

• Creates suction that can pull in prey from as far away as 1⁄2 - 3⁄4 head lengths away
  Extremely high suctions by Venturi effect (creating vacuum)
  Faster than swimming and can increase
  attack speeds by up to 40%

Question 6

Jaw protrusion phases

Answer 6

1. Preparatory phase
2. Expansion phase
3. Compression phase
4. Recovery phase

Question 7

Jaw protrusion Preparatory phase (1)

Answer 7

– Buccal cavity pressure increased resulting from inward squeezing suspensorium (cheeks and gills), and raising mouth floor (tongue)

Question 8

Jaw protrusion expansion phase (2)

Answer 8

Lower jaw depressed, premaxilla protrudes, suspensorium expands and mouth floor lowers creating high negative pressure or vacuum suction

Question 9

Jaw protrusion compression phase (3)

Answer 9

Pressure increases as mouth closes, bones move back into position while opercular valves open to release water under high pressure out of opercular opening (over the gills)

Question 10

Jaw protrusion recovery phase (4)

Answer 10

Bones, muscles and pressure in the buccal cavity returns to pre- preparatory conditions

Question 11

Fish jaws types

Answer 11

In non-protractible jaws
* Muscles work to expand buccal and opercular cavity and raise
the cranium
* Pulling mandible down pulls on the premaxilla via attachments to the maxilla

In protractible jaws
* As above, but premaxilla slides down a rostrum creating
longer narrower tube
* Elongated tube and negative pressure creates Venturi effect and thus strong suction

Question 12

Jaw protrusion patterns are based on what?

Answer 12

More than 8 different patterns based on:
- gape size,
- biting force,
- amount of protrusion
also 4 different pathways for mouth protrusion**

Question 13

Pharyngeal jaws

Answer 13

Moving water back to gills pushes food back to pharyngeal area
* In many Teleost (derived fishes), pharyngeal basket developed into extra jaws including teeth
* These fishes are called pharyngognathous
* Lower jaw formed from paired 4 - 5th ceratobranchial
(often fused)
* Upper jaw formed into dermal plate attached to epibranchial bones (top of gill arches)
* Induce secondary gape limitation

Question 14

How do pharyngeal jaws affect a fishes diet?

Answer 14

pharyngal jaws occur in very back of mouth (where closing looks in picture), mouth used to catch fish, pharyngeal jaws used to process.
this affects what a fish can eat because prey must fit in mouth and fit in pharyngel jaws; two factors

Question 15

Pharyngeal jaws purpose and shape

Answer 15

• Serve to direct, reposition, crush and disarticulate food
• Have teeth that vary by species but also by individuals
  within species (see dentition next)
• Different species have different shape, size and dentition of pharyngeal jaws
• Different pharyngeal jaw shapes in neotropical cichlids from geometric morphometrics analyses

Question 16

Dentition

Answer 16

Teeth arranged in one to several rows or patches
* Sometimes pointed and canonical (e.g., wolfish) , other times triangular and sharp and
serrated (sharks and piranhas)
* Teeth can also be modified into flattened plates arranged like paving stones for crushing (e.g., rays and some sharks)
* Which prey is targeted often predictable by teeth type

Question 17

Dentition
In bony fishes (teleosts)

Answer 17

Teeth are continuously replaced, sometimes in blocks or rows

highly variable with some families and species with no teeth (e.g., sturgeon), to several tooth spiked bony plates (e.g., monkfish)

can also be hinged (e.g., pikes and hakes), where teeth can bend inwards when passing prey but spring back by elastic ligaments to prevent escape

Question 18

Dentition types

Answer 18

Caniniform teeth
Villiform teeth
* Cardiform teeth
Molariform teeth
Beak-like

Question 19

Caniniform teeth

Answer 19

• Recurved with sharp points
• Serve to hold and grasp prey (e.g., Tigerfish - Hydrocynus
  vittatus)
• Especially useful to subdue struggling prey (in piscivores)

Question 20

Villiform teeth

Answer 20

-common for small fish
- Numerous small needle-like teeth,
- In surface-dwelling or benthic predators (e.g., pike, lizardfish)
- Like sand paper – helps grasp prey into buccal cavity (piscivores, zooplanktivores, insectivores)

Question 21

Cardiform teeth

Answer 21

• Fine pointed teeth arranged closely together (e.g., Snook,
  Largemouth bass, billfishes - Tunas)
• Typical in chase down and swallow-whole predators - Mostly designed to reduce escapement

Question 22

Molariform teeth

Answer 22

• Pavement / molar like flattened crushing teeth
• For hard prey items like gastropods, molluscs, sea-urchins, etc.. (e.g., horn shark, freshwater drum)

Question 23

Beak-like

Answer 23

• Teeth closely packed incisor types forming a beak (e.g.,
  parrot fish)
• Can be fused or separated
• Typically accompanied by hard molariform teeth more posteriorly
• For hard prey / food items such as coral and encrusted prey like barnacles etc.., (e.g., triggerfishes)
  23

Question 24

Gillrakers

Answer 24

Cartilaginous projections pointing inward and forward along the inner edge of gill arch
Highly heritable trait in many fish types (e.g., coregonids, cichlids, gasterosteiformes, etc,..)
Structures that aid in capture and retention of engulfed prey

Question 25

Gillrakers in coregonids study

Answer 25

* In lakes with 1 species, LSR fish with gill raker average numbers 18-34 found in all depth zones * In lakes with 3 species, Gill rakers averages by zones are very different

Question 26

Gillrakers in coregonids study results

Answer 26

proof theres a link in food, habit they use, and gill rakers since different types of fish in different zones had different gill raker average numbers

Question 27

Mouth Positions

Answer 27

Terminal mouths Superior mouths (supraterminal) Inferior mouths (subterminal) Suctorial mouths

Question 28

Terminal mouths

Answer 28

- body terminates in mouth where upper and lower jaw align - Chasers / filterers / siphoners

Question 29

Superior mouths (supraterminal)

Answer 29

- lower jaw extends more anterior than upper - Good for feeding on surface prey capturing from underneath

Question 30

Inferior mouths (subterminal)

Answer 30

- upper jaw extends more anterior than lower one - Feeding by either picking or scraping

Question 31

Suctorial mouths

Answer 31

- Designed for sucking / scraping surfaces in high energy environments

Question 32

Combined locomotory and feeding morphology

Answer 32

Mouth and feeding morphology and overall body shape morphology outline much of the functional features or functional morphology of fishes Can be used to make important inferences on typical feeding types or guilds among fishes and help understand the ecology of given species Also allows a better understanding of how fish use their environments and what features in those environments have likely shaped the fish’s evolutionary history

Question 33

Feeding types Zooplanktivores

Answer 33

* Small streamlined torpedo shaped bodies * Terminal and protractible mouths forming a funnel * Forked tails, with high aspect ratios (AR) for fast and sustained swimming * Mostly lacking in significant teeth * Many thin long, tightly packed gill rakers ex; herring, mackerel

Question 34

Feeding types Lurking ambush piscivore

Answer 34

* Elongate (tube-like) bodies * Long jaws with many sharp projecting teeth to grab and hold prey * Broad tails with mid-level AR for fast burst pushes * Posteriorly placed median fins set far back * Reduced gillrakers, ex; pike, barracuda