Zoology final exam

What are the 5 Chordate characteristics?

1. Notochord

2. Dorsal tubular nerve cord

3. Pharyngeal slits or pouches

4. Endostyle or thyroid gland

5. Muscular postanal tail

What is a notochord?

• fluid-filled cells that form a dorsal stiff, but somewhat flexible rod

• A precursor to the vertebrate backbone - but the notochord appears in all vertebrate embryos

What did mammals branch off from? And when?

branched off the vertebrate line in the late Paleozoic

How many lamellae of gills do teleosts have?

4

Why are teleost gills so feathery looking?

They need a larger surface area for oxygen extraction from sea water

Clownfish an sea anemone have a mutalistic relationship. List 2 benefits the fish might get from the sea anemone and then 2 things the anemone might get from the fish.

• Clownfish gain protection and a safe home

• sea anemone gain nutrient exchange and get cleaned by the fish

Describe how a pipefish locomotes.

• Dorsal fin and anterior fin (near gills) flaps

• head does more of movement by whipping head back and forth

How many gill openings are there in teleosts?

2

How many gill openings are there in sharks?

varies between 5, 6, or 7

• typically 5

How many gill openings are there in lamprey?

7

Why do the sharks have fewer gill slits than the lamprey?

They are vertebrates so they have a jaw, which leads to a shift in gill function/structure

How many caudal fins do lamprey, sharks, and teleosts have?

They all have 1

How many anal fins do lamprey, sharks, and teleosts have?

Lamprey have 0, but sharks and teleosts have 1

How many pectoral fins do lamprey, sharks, and teleosts have?

Lamprey have 0, sharks and teleosts have 2

How many pelvic fins do lamprey, sharks, and teleosts have?

• lamprey 0

• Sharks 2

• Teleosts 1

How many dorsal fins do lamprey, sharks, and teleosts have?

• lamprey ½

• Sharks 2

• Teleosts 1

Humans have selected guppies for long showy tails. Do you think this affects their swimming abilities?

Yes, more weight on the rear end is more likely to cause swim bladder syndrome, when the fish has trouble maintaining buoyancy

What is a dorsal tubular nerve cord?

initially hollow, but cavity often obliterated with growth

How do guppies swim?

Move tails side-to-side, wave-like motions. This starts near the middle of the body and pushes through the tail, propelling them foward

Catfish are a monophyletic superorder of mostly benthic (bottom-dwelling), detritivorous fish with thousands of species (we are unsure of which species we have). What obvious anatomical features distinguish catfish from guppies, and how might these relate to their habitat?

• Guppies are smaller (faster), brighter in color.

• Catfish have a more flat body for navigation and a casual fin to help propel them forward

What is the dorsal tubular nerve cord protected by?

Vertebral column in vertebrates

Consider the guppy and the catfish. Which fish do you think would be better adapted to swim some distance?

• Catfish because they’re larger/have more endurance

• guppies are better suited for shorter distances/faster swimming

What are pharyngeal slits/pouches

evaginations of the pharynx gill slits in fish, pouches other structures like parts of the ear in terrestrial vertebrates

Where is the endostyle/thyroid gland located and what does it do?

• On the pharyngeal floor. Secretes mucus to trap food or as a gland, secretes hormones

How does the pipefish feed?

By sucking live prey

• sucks/chomps prey quickly

What are teeth used for in the lamprey?

Parasitic attachment

What are the teeth used for in teleosts?

Grasping prey

Why do you think the shape of the pipefish is advantageous, given that its mode of locomotion (and hence escape from predators) is obviously slow?

It is thin and small, allowing it to fit in smaller spaces and hide

What is the muscular postanal tail used for?

Propulsion

What species belong to the Chordate subphylum Urocordata?

~3000

What subphylum do tunicates belong in?

Urochordata

Describe the life stages of a Urochordata.

Most adults are sessile, larvae are planktonic

What is the pathway food takes in a Urochordata?

water enters the top, depositing food on a mucus–bearing endostyle on the pharynx, exits an excurrent siphon

Describe the circulatory system of a Urochordata.

heart and circulatory system, and single nerve ganglion

Describe the reproduction system of Urochordates.

hermaphroditic

What reveals the relationship between adult urochordates and chordates.

Larvae

What class of animals do sea squirts belong to?

Ascideacea

What are the commenest tunicates?

Ascideacea (Sea squirts)

Describe the metamorphosis a larvae tunicate undergoes before becoming an adult.

• larvae is not a vertebrate 

  • notochord disappears  

    • becomes sessile polyp (no longer free swimming) 

Describe the circulatory system pathway found in the subphylum Cephalochordata

• Fully closed circulatory system: heart —> paired aortas —> capillaries —> veins —> heart

What subphylum do lancelets belong in?

Cephalochordata

How many species belong to the Cephalochordata subphylum?

~32

Describe the pathway of food seen in Cephalochordates as they feed.

• water taken in the mouth, passed over the sticky pharyngeal endostyle, and then expelled through the pharyngeal slits

How do Cephalochordates locomote?

By flicking posterior portion like fishes —> flipping

Describe reproduction in a Cephalochordate.

• Dioecious with external fertilization

Why does blood have hemoglobin in vertebrates?

to carry respiratory gases from or to gills or lungs.

Why does the gut become muscularized in vertebrates?

to process large food material

Why does the brain become 3-parted in vertebrates?

To sponsor active, predatory lifestyles

What are the three parts of a vertebrate brain?

1. Fore

2. Mid

3. Hind

How are sensory appendages grown in vertebrates?

They develop from interactions between neural and epidermal tissue

What are the sensory appendages seen in vertebrates?

• Olfactory

• Auditory

• Visual

What are the earliest vertebrates?

Agnatha

What were the earliest agnathans?

Ostracoderms

Agnathas were small, but they had sophisticated ___________ and ____________.

dorsal nervous system and sense organs

When were Agnatha prominent? What made them disappear?

Prominent for most of Cambrian period, before jawed fishes appeared

How did Agnatha apparently feed?

• hoovered up organisms/organic material from substrate, though some predatory

What phylum of fish are remnant of Agnathas?

Cyclostomata

What is the scientific name for Hagfishes?

Myxini

How many species belong to the Cyclostomata subphylum?

~78 MARINE ONLY species

How specifically are Cyclostomata remnant of agnathas?

Secondary loss of many vertebrate characters, e.g. no vertebrae in adults, but rudimentary ones in hagfish embryos

What does the Saprophagous feed on?

Strictly things dead/dying

• fish,

• marine mammals (especially whales)

When did hagfishes lose many genes?

After hexaploidization of genome in cyclostome evolutio

Which subphylum of Chordates are major producers of slime?

Cyclostomata

Which subphylum of Chordates are blind but have great olfactory senses?

Cyclostomata

What happens as a Cyclostomata goes through embroyonic life?

• somatic cell lineages lose many genes

Which animal features 7 gill slits?

Lampreys

What subphylum of animals do lampreys belong to?

Petromyzontida

What negative effect did lampreys have on the Great Lakes specifically?

decimated fisheries (especially lake trout)

Describe an adult lamprey.

Adults are about half of species are major parasites of fish: attach & suck like leeches

Niagara Falls Petromyzontida had no upstream migration until _____________.

The Welland Canal deepened in 1910s

Describe how Lamprey’s are controlled.

fishing (for their food) + specific larvicides applied to streams

Lampreys have anadromous life cycles. What does this mean?

eggs laid in streams, larvae burrow in substrate, adults move to ocean but can remain in lakes

What are the two major groups of Modern fishes?

1. Chondrichthyes

2. Osteichthyes

Describe what the Osteichthyes group of fishes includes.

“Bony fishes”

• Actinopterygii (ray-finned fishes)

• Sarcopterygii (coelacanths, lungfishes, tetrapods)

Describe what the Chondrichthyes group of fishes includes.

“cartilaginous fishes”

• Elasmobrachii (sharks, rays, skates)

• Chimaeras

What is the biggest ray?

Manta ray

What are some characteristics of a Manta ray?

• move through oceans by flapping fins like a bird flaps its wings

• filter feeders: harmless 

Where can sting rays typically be found?

Tropical areas below the tide line

How big do whale sharks get? Can they harm us?

Up to 60 feet

• filter feeders: harmless

How big does a hammerhead get?

Up to 19 feet

Hammerhead shark’s have eyes on either side of their head. What does this mean?

They have excellent binoculars vision

Female sharks are ovoviviparous. What does this mean?

Internal fertilization creates eggs, which are retained, hatched internally and then birthed live young.

Sharks bodies features a Streamlined shape. What does this mean?

• optimal for minimum drag = maximum speed

What’s special about shark teeth?

continually produced and shed

Why is it beneficial for an animal to buoyant?

Saves a lot of energy

What makes sharks naturally buoyant?

high lipid content

What forces sharks down? And how is this counteracted?

Asymmetrical tail forces shark downward

• counteracted by angling pectoral fins

What do shark’s dorsal fins help prevent?

yawing, i.e. help straight-line movement

How do male sharks inseminate females?

males have claspers to grab females and inseminate them

Many sharks have low ________ and are ____________. Meaning?

Many sharks have low fecundity (# of offspring) and are long-lived

Making them vulnerable to exploitation.

What is a green sharks lifespan?

400-500 years long

What do some people do to sharks in Asia? Why?

• heavy exploitation and release of finless animals!! (They catch them, cut their fins off, and then throw them back in the water

• Because shark fin soup is a delicacy there

Sharks have two anterior pharyngeal arches that become what?

• become the jaw so they only 5 functional gill arches total

What are the two novel sensory organs of sharks?

1. Lateral line

2. Ampullae of Lorenzini

What does the Ampullae of Lorenzini in sharks do?

sense bioelectric fields of potential prey organisms (only in sharks and rays)

What is the purpose of the lateral line?

• for predators but also found in prey as well to help them escape (ie. Ray-finned fishes) 

Describe what the lateral line is and how it works.

Sensitive to pressure of liquid; purpose is to sense changes in pressure all wound them, so when the sharks senses something struggling in the water, it creates a pressure in the water which they are sensitive to

What extremely unique thing do most electric rays do?

generate mild electric fields due to nerve and muscle activity

What is the difference between the electric fields produce by FW electric rays and SW ones?

• high voltages: generated in FW —> gets up to a couple hundred volts

• salt water is very conductacted so they build up high currents by stacking instead of generating high voltages

What structure do the lungs develop from in tetrapods?

gut diverticulum