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Ichthyology
2nd midterm
73
Biology
Undergraduate 4
11/12/2013

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Term
Gill membrane
Definition
Membranes covering the gill openings, attached to the branchiostegals
Term
Branchiostegal
Definition
Bony rays supporting the gill membrane behind the lower jaw
Term
Isthmus
Definition
The fleshy projection of the body separating the gill openings
Term
Gill arches
Definition
The bony arches to which the gills are attached
Term
Gill filaments
Definition
A series of projections along the posterior edge of the gill arch; the site of gas exchange
Term
Gill rakers
Definition
A series of appendages along the anterior edges of gill arches, they are different in each type of fish species (may be especially prominent in filter feeders)
Term
Pitch (fish movement)
Definition
Movement up and down
Term
Yaw (fish movement)
Definition
Movement from left to right
Term
Roll (fish movement)
Definition
Movement of the entire body at a slant
Term
Strouhal number
Definition
A measurement of swimming efficiency. The frequency of tail flapping times the jet's width, divided by the fish's speed. A Strouhal number between 0.25 and 0.35 is a hallmark of efficient swimming.
Term
What are the three types of scales?
Definition
Placoid, ganoid, and cycloid.
Term
Placoid scales
Definition
Teeth-like scales found in sharks and rays
Term
Ganoid scales
Definition
Armor-like scales coated with ganoin found in bichirs and gars.
Term
Cycloid scales
Definition
A smooth-edged scale, found in most fishes that we are used to seeing today. Ctenoid scales are a type of cycloid scales that have a rough edge.
Term
What are the four types of swimming?
Definition
Labriform, Carangiform, Anguilliform, Ostraciform.
Term
Labriform
Definition
Swim using the pectoral fins, common in wrasses and surf perch.
Term
Carangiform
Definition
Swim using the caudal fin, body is stiff. Very fast swimmers, such as tuna and jacks
Term
Ostraciform
Definition
Oscillate their caudal region, making them relatively slow. Boxfish, torpedo rays, Oceanic sunfish.
Term
Anguilliform
Definition
The type of swimming found in eels
Term
Mayr's Biological Species Concept (BSC)
Definition
Species are groups of actual or potential interbreeding natural populations that are reproductively isolated from other groups.
Term
Dobzhansky's Biological Species Concept (BSC)
Definition
Species are the largest and most inclusively reproductive community of sexual and cross-fertilizing individuals that share a common gene pool.
Term
What are three problems with the Biological Species Concept approach?
Definition
1. Not applicable to asexual species
2. reproductive isolation is often incomplete (hybridization is common among many groups)
3. Multidimensional concept is difficult to verify (how to we assess the potential to interbreed?)
Term
Phyologenetic Species Concept
Definition
by Joel Cracraft, The smallest diagnosable monophyletic group of populations within which there is a parental pattern of ancestry and descent.
Term
What are some problems with the Phylogenetic Species Concept?
Definition
1. What characters to use?
2. What level of divergence constitutes a species?
3. Distinguishing between gene trees and species trees
4. Does not address the mechanism.
Term
An example of a general species concept
Definition
Hausdorf (2011) said that species are groups of individuals that are reciprocally characterized by features that would have negative fitness effects in other groups and that cannot be regularly exchanged between groups upon contact.
Term
Prezygotic isolation
Definition
When barriers between populations act to prevent fertilization
Term
Postzygotic isolation
Definition
Barriers that do not prevent fertilization, but offspring are inviable or sterile
Term
What are the four modes of speciation?
Definition
1. Allopatric
2. Peripatric
3. Parapatric
4. Sympatric
Term
Allopatric speciation
Definition
Speciation that occurs when biological populations of the same species become isolated from each other to the extent that prevents or interferes with genetic interchange. Could be the result of population dispersal leading to emigration, or by geographical changes such as mountain formation, island formation, or large scale human activities.
Term
Peripatric speciation
Definition
A form of speciation in which new species are formed in isolated peripheral populations, but one opulation is much smaller than the other.
Term
Parapatric speciation
Definition
The population of a species constitutes one or more biogeographically distinct subpopulations with a small, continuous overlap or minimal contact zone between populations. This minimal contact zone may be the result of unequal dispersal or distribution, incomplete geographical barriers or divergent expressions of animal behaviors. A parapatric population may result in nonrandom mating and unequal gene flow, which can then produce an increase in the dimorphism between populations. There is an intrinsict barrier of nonrandom mating and distinct selection pressures that create unequal gene flow. Parapatric speciation is the culmination of this unequal gene flow effect, in which genotype dimorphism between populations results in speciation of the population and redefines the population as two or more sister species.
Term
Sympatric speciation
Definition
The process through which new species evolve from a single ancestral species while inhabiting the same geographic region.
Term
What are four components that lead to speciation?
Definition
1. Geographic
2. Ecological
3. Sexual
4. Genomics
Term
Haldane's rule
Definition
1. The magnitude of prezygotic and postsygotic isolation both increase with time.
2. Among recently separated groups, prezygotic isolation is generally stronger than postzygotic isolation.
3. In the early stages of speciation, hybrid sterility or inviability is almost always seen in the heterogametic sex.
Term
Dobzhansky-Muller incompatibility
Definition
The mechanism that causes postzygotic isolation
Term
What are the five requirements for sympatric speciation?
Definition
1. Sympatric distribution
2. History of allopatry is unlikely
3. Monophyletic sister taxa
4. Reproductive isolation
5. Pre-zygotic isolation
Term
Parental care in fishes
Definition
- Relatively common
- Most (78%) is uniparental
- Most are external fertilizers (89%)
Term
Sneaking
Definition
- Sneaking a spawn with another individual
- Most common for males to sneak spawn with the fmales from someone else
- Increases fitness with very little parental care
- Results in lekking and nesting (like seen in the Ghiribaldi)
Term
What order do the senses go in fish (by distance)?
Definition
- Hearing
- Smell
- Vision
- Lateral line
- Electroreception
- Touch and taste
Term
What order do the senses go in fish (by distance)?
Definition
- Hearing
- Smell
- Vision
- Lateral line
- Electroreception
- Touch and taste
Term
In what two ways are senses used?
Definition
To understand the environment (ex: to hear)

To display in the environment (ex: to produce sound)
Term
Sound perception in fishes
Definition
Happens in the inner ear.

Different parts of the hearing organ have different densities. When a sound wave is received, they vibrate but with different inertias. In doing so, they stretch the nerves that connect them to each other. The brain interprets this as sound.
Term
Sacules
Definition
Found in the hearing organs of fish, large loops filled with gel, connected by nerves to the otoliths
Term
Sacules
Definition
Found in the hearing organs of fish, large loops filled with gel, connected by nerves to the otoliths
Term
Otoliths
Definition
Three of them, found in the hearing organ of the fish.

Made with crystals, very heavy compared to everything else in the fish. Connected to sacules in the hearing organs.

When sound arrives, the medium around the sacules and the otoliths move differently because of the differing densities.
Term
Otoliths
Definition
Three of them, found in the hearing organ of the fish.

Made with crystals, very heavy compared to everything else in the fish. Connected to sacules in the hearing organs.

When sound arrives, the medium around the sacules and the otoliths move differently because of the differing densities.
Term
Weberian Apparatus
Definition
Found in otophysi, an adaption that is used to improve sound perception.

The first four vertebrate have appendages coming off of them that attach the swim bladder to the hearing apparatus, so when a noise is processed it rattles the swimbladder.

This is well developed in Otophysi because the vast majority of them live in murky fresh waters.
Term
Swimbladders for sound production in fishes
Definition
Some fish (such as drums) have muscles that bang on the swimbladder to make noise.
Term
Swimbladders for sound production in fishes
Definition
Some fish (such as drums) have muscles that bang on the swimbladder to make noise.
Term
Pharyngeal jaws for sound production
Definition
Animals grind the pharyngeal jaws.
Term
Smell in fishes
Definition
In general, fishes have two holes on each side of their snout. Water goes in one nostril (for each side of the snout) and goes through a complicated pathway that is highly vascularized inside of the nostril before it goes back out. The tissue is full of knobs that are full of nerve endings and taste buds. All this makes the animal capable of smelling very well.
Term
Schrekstoff
Definition
Found in Ostaryophysi. When they are scared they produce a hormone that has a specific smell. By producing this hormone they are warning all the individuals of their own species that something is going on. This causes everyone to panic at the same time and the predator is confused. The hormone is very conserved among all the ostaryophysi (so you can scare a group of minnows, transfer the water from the minnow tank to a tank of goldfish, and they will all start freaking out)
Term
Eye of a deep sea species
Definition
Structure is very similar to ours. Retina is split in two, one part is thick and the other part is thin. The thin portion is helpful for seeing downwelling light, and the thicker portion is useful when looking into the darkness (forward), so it can capture more light. The thickness of the lens is also thinner at the front and thicker at the back.
Term
Eye anatomy of an Anablep
Definition
There is an adaption so that where the eye is above the water and will be in contact with air, the cornea is very thick. The bottom portion that is underwater is thinner. Almost as if they have two eyes in one.
Term
Evidence that fish likely cannot see very sharply
Definition
Placeops has an ocelum (a mark on the dorsal fin that looks like an eye), with fin flared it is supposed to mimic a moray eel.

It would be difficult for us to be fooled by these adaptations, but apparently it works for fishes.

Another example is the ocelum found on the Foureye butterflyfish.
Term
What is the function of having different colors of juveniles and adults?
Definition
In experiments, when babies were the same color as the adults, the adults killed them, because they compete with other adults for food and would fight over resources (with the juveniles not having much of a chance)
Term
Sexual selection in fishes
Definition
Females are very sensitive to color in fishes. Therefore, males display in specific areas that enhance specific colors.

Ex: Labriform swimming in wrasses allows the males to flash color underneath the pectoral fins at the females.

Ex: Rainbow surf perch has a large abdomen that can be flashed in areas where rays of light come from the top.
Term
What are the two types of cones found in the eyes of fish?
Definition
Luminance component (light) or chromatic component (color).

Humans have a mixture of both.

Underwater as depth increases, colors become invisible. It becomes darker as depth increases because a lot of our cells are not being used (ex: the cells that are used to see red aren't being used because there is no red).

Squirrelfishes are well adapted to specific depths (different species are found at specific depths). All of the cells in their retina are attuned to the wavelength of color that is reaching that depth.
Term
Why is it a benefit for fish to have larger eyes to see prey?
Definition
Prey need to hit a certain number of cells in the retina before it can be detected. When fish have a larger eye they have more of those cells.
Term
Lateral line
Definition
A way of feeling pressure waves in the water. Not all fishes have it, but many do. It is a sense that is not found in humans. Along the side of the body are specialized scales with a tube/opening in them that allows the sound vibration or pressure waves to travel in the water and be sensed by sensory hairs (cupula) at the tips of nerves, which send a signal to the brain. This is felt as movement and is used both passively and actively.

Ex: Fish can use their lateral lines to feel an animal that is wounded nearby. They can also feel where other animals are in relation to themselves and it is used in courtship systems where animals are shaking their heads, doing dances, quivering...
Term
What are the two ways electroreception is used in fishes?
Definition
- To understand/assess the environment
- To send strong electrical signals to stun/kill prey
Term
Amupllae lorenzini
Definition
Structures that are gel-filled areas, connect with nerves, can distinguish very well some weak electromagnetic fields (produced by the twitching of muscles of other animals).

Found in sharks.

Some fish can sense the electromagnetic fields of beating hearts of other fish under the sand.
Term
Threshold R
Definition
Smallest R needed to trigger sex change.

R = number of fish smaller than sex change candidate in social group / number of fish larger than sex change candidate in social group
Term
Protandrous Hermaphrodites
Definition
Ex: Clownfish

Change from male to female
Term
Protogynous hermaphrodites
Definition
Change from female to male

Ex: wrasse, parrotfish
Term
Simultaneous hermaphrodite
Definition
An adult that has both male and female sexual organs at the same time

Ex: Hamlet
Term
What are the three types of unisexual species?
Definition
Hybridogenetic (each offspring contains male and female DNA but the egg loses the male DNA and is an exact clone of the egg that produced it)
Gynogenetic (Sperm is used to trigger reproduction, but each individual contains only DNA from the female and is a clone of the animal that produced it)
Parthenogenetic (no male sperm is needed)
Term
Fitness
Definition
Viability + Fecundity + Longevity + Mating Success
Term
Gonopodium
Definition
A modification of the anal fin in males of certain live-bearing species. Is used to transfer sperm to the femal eduring mating.
Term
Raptorial jaws
Definition
Found in Moray Eels, when the pharyngeal jaw can be brought far up into the mouth from the throat.
Term
Retractor dorsalis (RAB)
Definition
A muscle that allows greater control over the pharyngeal jaws so they can be used for sorting, etc.
Term
Physostomous swimbladder
Definition
Connected to the esophagus by a pneumatic duct
Term
Physoclistous swimbladder
Definition
Not connected to the gut; more efficient; takes more time for ascent (air has to re-enter the bloodstream by diffusion)
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