Biology 2 Practical 3

Vomerine teeth

Two teeth on the roof of the frog's mouth; hold, crush, and break the exoskeletons of prey

Maxillary teeth

Small teeth along the upper jaw of the frog; angled inward to grip prey and prevent escape

Tympanum

The external eardrum of the frog; receives sound vibrations and transmits them to the brain

Nictitating membrane

Transparent protective membrane attached to the bottom of the frog's eye; protects the eye when submerged

External nares (frog)

Two small openings on the frog's head that assist in breathing; allow air in with the mouth closed

Internal nares (frog)

Internal openings connecting to the lungs; allow the frog to breathe with its mouth closed

Glottis (frog)

Opening/tube leading to the lungs in the frog; aids in breathing and vocalization

Tongue (frog)

Sticky, attached at the front of the mouth; catches prey — does NOT aid in swallowing

Eye bulges (frog)

Protrude into the mouth cavity; push food down the frog's throat to aid swallowing

Why are frog eyes on top of the head?

To allow the frog to see predators and prey from all directions simultaneously

Frog hind limbs

Longer and more muscular than forelimbs; webbing between 5 toes increases surface area for propulsion in water

Frog fore limbs

Shorter, 4 toes; support the frog at rest and absorb impact when landing after a jump

Frog heart chambers

3 chambers: right atrium, left atrium, and one ventricle; oxygenated and deoxygenated blood MIX in the ventricle

How does air enter frog lungs?

Buccal pumping — the floor of the mouth is pushed up, forcing air into the lungs

Frog lungs

Used for gas exchange; the skin also assists with gas exchange via numerous blood vessels

Frog liver (3 lobes)

Secretes bile; monitors levels of digested food in the blood; stores excess products of digestion

Frog stomach

Muscular breakdown of food; secretes strong acids for chemical digestion

Frog small intestine

Finishes digestion; primary site of nutrient absorption into the blood

Frog large intestine

Absorbs water; moves waste toward the cloaca

Male frog ID

Has testes (produce sperm) and vocal sacs (used to attract mates and establish territory)

Female frog ID

Has ovaries (produce eggs) and oviducts (coat eggs in a jelly-like material for protection)

Tympanum size — male vs female frog

Male: tympanum is larger than the eye. Female: tympanum is equal to or smaller than the eye

Olfactory bulb (frog brain)

Responsible for the sense of smell; poorly developed in frogs

Cerebral hemisphere (frog brain)

Controls voluntary actions (e.g. jumping); center of memory, intelligence, and consciousness

Optic lobe (frog brain)

Functions in vision

Medulla (frog brain)

Regulates involuntary/autonomic functions such as respiration and digestion

What group is the frog?

Amphibian — ectothermic vertebrate; lives in both terrestrial and aquatic environments; breathes with lungs on land and gills in water

Pigeon beak

Composed of upper beak and lower beak; short, thick, and cone-shaped to crack seeds and nuts; used to grasp/crush food, defend, and manipulate objects

Pigeon tongue

Piston tongue; primarily aids in drinking; has some taste buds

Pigeon crop

Temporarily stores food; begins pre-digestion before food enters the stomach

Pigeon gizzard

Mechanically breaks down food through muscular contractions of the gizzard wall; acidic secretions create chyme passed to the small intestine

Pigeon intestine

Site of final digestion and absorption of nutrients

Pigeon cloaca

Single posterior opening for the digestive, urinary, and reproductive tracts; expels feces and lays eggs

Pigeon liver

Responsible for metabolism, excretion, detoxification, and synthesis of biochemicals

Pigeon heart chambers

4 chambers (2 atria + 2 ventricles) with a complete septum; "double circuit" heart with complete separation of oxygenated and deoxygenated blood

How do pigeon lungs differ from other vertebrates?

Pigeon lungs are rigid and non-elastic — they do NOT store air; they rely on air sacs to move air through (flow-through ventilation)

Pigeon lung ventilation type

Flow-through ventilation — air sacs move air through the rigid, non-elastic lungs

What group is the pigeon?

Reptile (bird) — vertebrate, scales/scutes, oviparous (egg-laying); exception: endothermic unlike most reptiles

Perch first dorsal fin

Anterior dorsal fin; has sharp spines; functions for protection and balance

Perch second dorsal fin

Posterior dorsal fin; functions for balance and stability

Operculum (perch)

Bony plate that protects the gills; also pumps water over the gills when the fish is not moving

Perch caudal fin

Propels the fish forward; provides power for swimming

Perch pectoral fin

Steers the fish; controls swimming depth

Perch pelvic fin

Stabilizes the fish; allows up-and-down movement in the water

Perch anal fin

Provides stability

Perch heart chambers

2 chambers: 1 atrium and 1 ventricle; single loop circulatory system

Perch circulatory system

Single loop — blood flows to and from the heart in one pathway; oxygenated and deoxygenated blood are NOT in separate pathways (unlike other vertebrates)

Countercurrent flow (perch gills)

Water moves across the gills in the opposite direction of blood flow; maximizes oxygen extraction efficiency

Swim bladder

Adjusts the amount of gas inside to control buoyancy; allows the fish to remain at a given depth without effort

Perch gills

Allow the fish to breathe underwater via gas exchange; use countercurrent flow

Perch liver

Regulates blood glucose levels; aids digestion via enzyme secretion; detoxification

Perch stomach

Breaks down food and absorbs nutrients; receives food from the esophagus

Perch intestine

Final digestion and absorption of food; relatively short because fish proteins are easy to chemically digest

Perch gonad

Sex organs — males have 2 testes (sperm production); females have 1 ovary (egg production)

What group is the perch?

Fish (Osteichthyes/bony fish) — ectothermic vertebrate; breathes with gills; has a swim bladder; uses fins for movement