- Placoid: shark - Ganoid: rhomboid - Ctenoid: comb-like - Cycloid: rounded

Lab Quiz II Flashcards by Mikayla Homesley

List the classes in Superclass Agnatha in order of appearance.

Ostracoderms*
Myxiniformes
Petromyzontiformes
Conodonts*

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List the classes in Superclass Gnathostomata in order of appearance. Include subclasses where applicable.

Placodermi*
Chondrichthyes
- Elasmobranchii
- Holocephali
Osteichthyes
- Actinopterygii
- Sarcopterygii

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What are the anatomical features of class Chondrichthyes?

Placoid scales
2-chambered heart
Cartilaginous skeleton

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What are the anatomical features of Chondrichthyes that ais in swimming and buoyancy?

Fin placement
Oily liver
Cartilaginous skeleton

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Sharks have high blood-urea concentrations. What does this help them do?

Osmoregulate, prevent dehydration by maintaining a slightly hyperosmotic state relative to the environment.

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What are the common anatomical features of elasmobranchii?

5-7 gill slits
Use a spiracle to bring water over gills
Sub-terminal mouth
Hyostylic suspension of jaw
Ampullae of Lorenzini (gel sacs, electroreception)
Cloaca (urogenital, anal)
Claspers
Internal fertilization

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What animals make up subclass elasmobanchii?

Sharks, skates, rays, sawfish

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What types of sharks are amphystylic jaws seen in?

“Primitive” sharks like frilled and 7-gilled sharks

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Skates vs. Rays

SKATES
- Thick tails
- Oviparous

RAYS
- Thin tail, some with stinging spine
- Viviparous

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What are the common anatomical features of subclass holocephali?

4 gills covered by a single opening
holostylic jaw suspension
Oviparous
separate anal and urogenital openings
Claspers (some on forehead)
Slime coat instead of scales

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What animals make up holocephali?

Chimera & ratfish

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What does holocephali mean?

“Whole head”

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What are the general characteristics of bony fish?

First appearance of endochondral bone
Operculum present (increases suction, water flow over gills, more powerful than only spiracle)
Swim bladder (offsets bone, most contain gas, sometimes lipid)

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Describe aspects of Actinopterygii.

Derived group
Fins supported by rays
Placement of pectoral fins not conducive to limb development

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Describe aspects of Sarcopterygii.

Ancestral group
Fins supported by fleshy, lobe-like stalk and contain true bones
Fin placement (pectoral, pelvic) allow for tetrapod limb development

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Heterocercal tail

Dorsal and ventral lobes are different sizes. Provides upward/downward drive.
Seen in Chondrichthyes and ancestral sarcopterygians.

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Homocercal tail.

Dorsal and ventral lobes are the same size. Most bony fishes.

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Scale types

Placoid: shark
Ganoid: rhomboid
Ctenoid: comb-like
Cycloid: rounded

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What does increased musculature allow for?

More planes of contraction
More varied movement
Increased movement

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What does the horizontal septum allow for?

Allows elasmobranchs to move their body within a single plane.
Has an antagonist group for the opposite movement.

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Epaxial muscle

Dorsal to HS.

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Hypaxial muscle

Ventral to HS.
Includes some vertebral muscles, diaphragm, abs, limbs

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Linea alba

CT separating L & R myomeres midventrally

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Abductor muscles

Pull way from midventral line

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Adductor muscles

Pull toward the midventral line

Spiracle

Opening between gill chamber and the environment. Not as effective as buccal pumping when used alone.

RAM ventilation

Sharks swim with mouth open to "ram" water over their gills. More effective in combination with spiracle. Associated with very active sharks

Gill SA for gas exchange is directly related to what?

Activity level

Gill types

- Gill lamellae: used to increase SA - Hemibranch (gill 1, posterior side has lamellae) - Holobranch (gills 2-5, both sides have lamellae)

Gill structures

- Gill rays: support for lamellae - Gill rakes: keeps food inside oral cavity separate from gills

Stomach rugae

Longitudinal folds that allow for expansion to accommodate a larger meal.

Where does protein breakdown start?

Stomach.

Pyloric sphincter

Separation point between stomach and intestine. Keeps stomach acid out of intestine.

Spiral valve

Increases intestinal SA Increases nutrient exchange

Pancreas

Secretes enzymes to breakdown proteins

Digitiform gland

Secretes salt, aids in excess salt removal.

Liver

- Aids in buoyancy due to large fat content - Digestive organ, detoxifies, metabolizes, and creates bile for digestion

Shark male reproductive anatomy

Paired testes Urogenital papillae Claspers

Female shark reproductive anatomy

Paired ovaries and oviducts Nidamental gland Uterus Urinary papilla

Shark seasonal breeders

Repro at one time of the year. Months-long gestation, then not pregnant the rest of the year.

Shark punctuated breeders

Often pregnant for a full year but spend 1+ years in-between non-pregnant.

Shark continuous breeders

Reproductively active all year long.

Oviparity

Egg-laying. Externally deposited eggs are leathery/durable

Viviparity

Live birth

Ovoviviparity

Eggs develop and hatch inside mother. Live birth.

Parthenogenesis

Clonal or "virgin" birth. Known because of zoos.

Yolk-sac nutrition

- Retention of fertilized eggs throughout development of embryo within the uterus - No other maternal input is supplied - Widespread among elasmobranchs

Histotrophy

- Initial nutrition by yolk-sac, then by “uterine milk” or histotroph - Can be limited “mucoid” or lipid rich

Placental

Most advanced form of embryonic nutrition

Oophagy

"Egg-eating." Unfertilized only.

Adelphophagy/embryonic cannibalism

Eat fertilized and unfertilized eggs

Lecithotrophy

Embryonic development supported only by yolk's nutrition

Matrotrophy

At least part of fetal development is supplemented by maternal input of nutrients.

Sensory systems from farthest to closest

- Chemoreception (taste, smell) - Mechanoreception (pressure, touch, vibration) - Vision (light stimuli) - Electroreception (E currents)

Regions of the tripartite brain

PROSENCEPHALON (fore) - Telencephalon - Diencephalon MESENCEPHALON (mid) - Optic lobes RHOMBENCEPHALON (hind) - Metencephalon - Myelencephalon

Spinal cord

Part of NS, contained in spinal column

Cerebrum

Most anterior brain. R/L hemisphere separated by a fissure. Integration of complex sensory and neural functions. Voluntary coordination.

Cerebellum

Back of skull Coordinates/regulates muscle activity

Olfactory sacs

For olfaction.

Cranial nerves

Come directly from the brain

Meninges

Membrane surrounding the brain, contains cerebrospinal fluid.