Download Marine Vertebrates: Lecture 3

Marine Vertebrates: Lecture 3
January 14, 2008
Class Osteichthyes: Subclass Actinopterygii: the ray-finned fishes
I.
Teleostei Diversity 1: Coral reef fishes
A.
Overview: Over 6000 species; approximately 40% of fish fauna (all groups)
B.
Coloration
1.
Types
a.
Chromatophores with pigments

How do they cause color changes?
b.
Iridiphores: structural; crystals within skin cells
2.
Functions
a.
Warning
b.
Sexual selection
c.
Camouflage

Some patterns made with bright colors are actually “disruptive”; broken
patterns help camouflage

Some color patterns truly blend in

Red in nocturnal fishes is actually a camouflage. What makes it so?
d.
Predator confusion

Silvery flash of silvery fish
e.
Countershading
C.
Herbivores (examples)
1.
Parrotfish
a.
mouth structure
b.
feed on turf algae on coral, as well as zooxanthellae within live coral (species
dependent)
c.
body shape
d.
role of pectoral fins in propulsion/maneuvering
e.
protection: secrete a mucous sac around them at night that traps their odors to
prevent detection
2.
Damselfish
a.
farmers
b.
small mouths, sharp teeth
c.
differences in territory sizes; territory overlap
d.
incredible at defense for their small size
3.
Tangs
a.
tang gangs
4.
NOTE: None of the herbivores are particularly fast; remain close to reef for
protection.
D.
Planktivores
1.
Creole wrasse
a.
protrusible mouth, “inhale” food with suction (common among Teleosts)
b.
streamlined, lunate tail: position slightly off-reef means a need for speed
2.
Seahorses
a.
mouth similar to creole wrasse; also use suction to feed.
b.
caudal peduncle (base of tail) is elongate for hanging onto substrate; swim with
dorsal fins, stabilize with small pectoral fins
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c.
d.
E.
F.
G.
ridges are bony rings for protection
males with brood pouch. Note that male parental care occurs in other fish as
well. We will discuss mating systems of seahorses and their relatives later…
3.
Yellowhead jawfish
a.
Planktivores that reside in/stay close to burrows of their own making
b.
Males are mouth brooders
4.
Garden eels
5.
Cardinalfish/blackbar soldierfish
a.
Nocturnal planktivore
b.
Large eyes allow them to capture the demersal zooplankton that migrates
vertically from the substrate at night
Omnivores (small prey, algae)
1.
Angelfish
a.
Cruise the reef feeding on sponges and algae
b.
Body shape allows for maneuvering within narrow reef crevices
c.
Travel in mated pairs
2.
Butterflyfish
a.
Use good eyesight and fine mouths to pick at small invertebrates within the reef
b.
Body shape similar to angelfish
c.
Dorsal spines deter predators
d.
Travel in mated pairs
Carnivores (mostly benthic invertebrates)
1.
balloonfish, porcupinefish, pufferfish
a.
Outer bones of jaws modified into beaklike structures for crushing coral and
other invertebrates
b.
Pufferfish are known for two things

ability to inflate. How do they do it?

tetrodotoxin (TTX): sodium channel blocker that causes paralysis

Where in the pufferfish’s body is it located?

NOTE: if you see “fugu” on the menu, beware…

Do all who are poisoned die?
2.
Goatfish
a.
Sift through sand with sensitive barbels for invertebrates
3.
Triggerfish
a.
Use jets of water to uncover sand-dwelling prey
b.
Trigger: “the stout first dorsal spine can be locked in place by depressing the
second spine, the trigger”
Carnivores
1.
Many groupers (i.e. Black grouper)
a.
Ambush predators use a combination of ram and suction as they lunge
explosively forward; larger adductor muscles of the jaw
2.
Moray eels
a.
Body form suited to move through cracks and crevices of the reef
b.
Feed on fish and invertebrates (even octopuses)
3.
Barracuda
a.
Lie-in-wait midwater predator
b.
Dorsal and anal fin set further back, broad compared to midwater pursuit fish:
allows for hovering in water column.
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II.
c.
Large (yet somewhat forked) tail allows for bursts of speed to ambush prey.
d.
Coloration: countershaded for camouflage
4.
Needlefish
a.
Surface-oriented predators that feed on small fish. Long jaw with sharp teeth
helps seize prey (note some similarities to barracuda body form)
5.
Scorpionfish and stonefish
a.
Toxins in hollow dorsal spines
6.
Shortnose batfish
a.
Has a lure that hangs off the snout-tip (stored in a depression) to catch prey
including fish and invertebrates (crabs, molluscs)
b.
Fins are modified so it actually walks, rather than swims!
H.
Parasitic
1.
Pearlfish
a.
One species lives within respiratory tree of sea cucumbers
b.
Digestive system curves so that anus is close to mouth; doesn’t have to emerge
far from cucumber to eliminate waste
c.
NOTE: Can also be commensal, with host providing a protective habitat
Teleostei diversity 2: Deep-sea fish
A.
Categories: mesopelagic vs. bathypelagic
B.
Focus: mesopelagic deep-sea fish (lanternfish = Myctophidae; hatchetfish)
1.
Vertical migrators: migrate along with zooplankton and feed upon it.
2.
Large eyes in proportion to body size with sensitive, rod-rich retinas
a.
Some with tubular eyes to aid in binocular vision, prey capture

May have double retinas oriented in different directions
b.
Large eyes also correlated with bioluminescence
3.
Silvery sides, and counterillumination with photophores on the bottom
4.
Well-developed skeleton
5.
Scales
6.
Swim bladder: present and often well-developed for regulating buoyancy while
traveling through large depth changes
7.
Very effective gills, circulatory system and kidneys, indicating high levels of activity
C.
Focus: bathypelagic deep-sea fish (deep-sea anglerfish, viperfish, gulper eel)
1.
Mostly lie-in-wait predators, relatively inactive
2.
Small eyes
3.
Coloration often deep-black, usually without photophores for counterillumination
a.
No light means no shadows
4.
Body composition:  proportion of water,  proportion of protein and lipid
a.
Is this an adaptation for flexibility or a consequence of low food levels?
5.
Skeleton is only weakly ossified, flexible
6.
No swim bladder
7.
Feeding adaptations
a.
Large mouths in relation to body size. How of benefit?

Viperfish has a hinged jaw that allows for a wide gape
b.
Pointed, rearward-facing teeth help to retain prey as in a trap
c.
Highly distensible bodies
d.
Anglerfish: bioluminescent pole and lure from first ray of first dorsal fin;
bioluminescence generated by symbiotic bacteria  used to attract mates
(males) as well as food, although males also use olfaction to find females
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8.
III.
Physiology adapted to deal with pressure.
a.
For example, pressure affects both enzyme-substrate binding and reaction rates.

Decreased pressure sensitivity of enzyme function in deep-sea fish

Appears to be at the cost of decreased efficiency (higher
activation energy/lower catalytic efficiency); however, enzymatic
activity in brain matches levels of other fish, so high efficiency is
possible.
b.
Proteins more resistant to change in 3-D structure
c.
Higher ratio of unsaturated: saturated fatty acids
Teleostei diversity 3: Pacific coast fish (selected for diversity or unusual body form)
A.
Rockfish
1.
All in the same genus, Sebastes, with roughly similar body forms including body
shape, fins, mouth.
a.
Mostly substrate oriented
2.
At least 72 species in NE Pacific out of 102 worldwide
3.
Niche partitioning: by depth, substrate and food
B.
Halibut
1.
Ambush predators similar in movement to angelsharks
C.
Mola mola
1.
Somewhat related to triggerfish
2.
Beaklike mouth; feed on midwater jellyfish
3.
Seen “basking” at surface
a.
One hypothesis: they are being cleaned of parasites by gulls
b.
Another hypothesis: the gull is unsuccessfully trying to eat it
D.
Midshipmen
1.
Abundant in Puget Sound
2.
California singing fish: generate sound with swim bladders
a.
Two types of males…
b.
Males (large ones) tend nests of eggs in the intertidal, shallow subtidal
E.
Flying fish
1.
Generate speed with lower lobe of caudal fin
2.
Glide with pectoral fins (escape response)
References
Bond CE, 1996. Biology of Fishes. Harcourt Brace College Publishers: Fort Worth, 750 pages.
DeLoach N, Humann P, 1999. Reef Fish Behavior: Florida, Caribbean, Bahamas. Florida: New World
Publications, 359 pages.
Humann P, DeLoach N, 1999. Reef Fish Identification: Florida, Caribbean, Bahamas. Florida: New World
Publications, 396 pages.
Love MS, Yoklavich M, Thorsteinson L, 2002. The Rockfishes of the Northeast Pacific. Berkeley: University of
California Press, 404 pages.
Moyle PB, Cech JJ Jr., 2003. Fishes: An Introduction to Ichthyology, 5th edition. Prentice Hall: New Jersey, 726
pages.
Nybakken JW, Bertness MD, 2004. Marine Biology: An Ecological Approach, 6th edition. San Francisco: Prentice
Hall, 579 pages.
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