vertebrates

Gnathostomes meaning

jawed mouth

Gnathostomes have a

true hinged jaw

The hinged jaw of Gnathostomes is considered to be one of their

novel traits

What is the other novel trait in Gnathostomes besides their hinged jaw?

paired pectoral and pelvic fins

The hinged jaw allows for

biting, grasping, tearing food

Two classes of Gnathostomes

chrondricthyes and osteicthyes

Class Chondricthyes consists of

sharks, rays and skates

Chondricthyes are exclusively a

marine species

Chondricthyes have a

cartilaginous bone, jawed fish

Chondricthyes endoskeleton composed of

cartilaginous bones

Body shape of Chondricthyes

dorsolaterally flattened, sleek fusiform bodies

Chondricthyes are generally

fast, active swimmers

Chondricthyes are almost exclusively

carnivourous, some are filter feeders

Chondricthyes intestine has

spiral valve that slows food passage

Chondricthyes have a ______ gland

rectal; secretes high conc of sodium chloride

Chondricthyes rectal gland helps kidneys with

osmoregulation

Chondricthyes scales

placoid

Placoid scales in Chondricthyes

- animal produces scales

- teeth evolve from this

- reduces turbulence

Chondricthyes, their cartilaginous body is

denser than water

Chondricthyes pectoral fin provides

lift

Chondricthyes livers

large livers that contain buoyant oils

Chondricthyes sensory system

well-developed

Chondricthyes, eye sight

excellent eyesight but colorblind

Some Chondricthyes eyes have

binocular vision

Chondricthyes smell

acute sense of smell

Chondricthyes, nostrils

2 nares/nostrils under snout

Chondricthyes ampullae of lorenzini

allows for rapid electromagnetic field detection

Chondricthyes lateral line

detects water motion

Chondricthyes Respiratory

gills

Chondricthyes gills have

increased surface area to ensure enough oxygen can be absorbed from water

Diffusion occurs from

high conc. to low conc.

Oxygen-poor blood flows

countercurrent to the flow of water across gills

Chondricthyes reproduction

sexual with internal fert

Male Chondricthyes have

claspers

Chondricthyes produce

few offspring at a time

Chondricthyes parental care

none provided to offspring

Chondricthyes offspring development

oviparous and viviparous

Chondricthyes Oviparous

all skates, some sharks

In oviparous,

- eggs covered in leathery case

- female lays fertilized eggs

In oviparous, the embryo receives nutrition from

egg yolk

Viviparous Chondricthyes

all rays, most sharks

In viviparous,

- live birth

- egg sack with embryo attaches to mothers oviduct

In viviparous, the embryo gets nutrition from

the mother

Chondricthyes, most are a special type of viviparous called

ovoviviparous

Ovoviviparous

- egg dev in mother

- embryo gets nutrition from yolk

- hatch/ fully developed in utero

- then mother gives birth

In ovoviviparous, the embryo receives nutrition from

the egg yolk instead of the mother

Superporders in Chrondicthyes

Selachimorpha and Batoidea

Superorder Selachimorpha

includes all sharks varying in size

Selachimorpha gills

5-7 gill slits on each side

Selachimorpha pectoral fins

are "free"

Selachimorpha mouth

armed with rows of serrated, pointed enameled teeth embedded in gums

Selachimorpha, teeth

first row is current teeth, following rows are replacement teeth

Selachimorpha speed

fast predators

Selachimorpha, cruising speed

10 mph

Selachimorpha, attacking speed

20 mph

Selachimorpha, mako top speed

30 mph

Selachimorpha, are they social?

yes

- travel in groups

- intelligent

Selachimorpha, regeneration of

neurons throughout life

Selachimorpha, family Lamnidate

- partially endothermic

- retain heat generated by muscles

In the family Lamnidate, are these sharks truly endothermic?

No, body temp is only kept a few degrees higher than water temp

Chondricthyes superorder Batoidea

rays and skates

Batoidea, mostly

bottom-dwellers with spiracles

Batoidea, spiracles

allow them to bury in sand and breathe

Batoidea, manta rays/devil rays

- extremely large and pelagic

- filter feeders

Batoidea, pectoral fins

enlarged and fused with head

Batoidea, caudal fins

adapted into whip-like tail for defense

Batoidea, whip-like tail

for lashing/puncturing

Batoidea, teeth

modded into flattened, spike bars for crushing

Batoidea, eat

crustaceans, mollusks, small fish

Batoidea, teeth are continuously

replaced like sharks

Class Osteichthyes

osseous bone, jawed fish

Osteichthyes are both

marine and freshwater sp

Osteichthyes body shape

laterally flattened

Osteichthyes scales

overlapping teleost scales

Osteichthyes scales grow

as the fish grows

Osteichthyes feeding habit

carnivorous, herbivorous, omnivorous

Osteichthyes, osseous bodies are

denser than water

Osteichthyes, bodies have

swim bladder for buoyancy

Osteichthyes sensory systems

well-developed

Osteichthyes eyesight

excellent, most can see color

Osteichthyes, individual species percieve

the colors typical of their environment

Osteichthyes, shallow water sp see more

color than deep/pelagic sp

Osteichthyes, smell

acute sense, 2 nares under snout

Osteichthyes, water flows into each nostril through

nasal sac and out nostril

Osteichthyes lateral line

receptors the same as hair cells in ears of land animals

2 classes of Osteichthyes

Actinopterygii and sarcopterygii

Actinopterygii are the

predominant subclass

Actinopterygii consists of

ray-finned fish

Actinopterygii fish have

long, thin endoskeletal bones in fins

Sarcopterygii are only

a few extant sp, very ancient

Sarcopterygii consists of

lobe-finned fish

Sarcopterygii fish have

short fleshy fins with thick bones and muscles in fins

Sarcopterygii are thought to have given rise to

terrestrial tetrapods

Osteichthyes reproduction

almost exclusively external fert via courtship spawning

Osteichthyes embryos develop

within the egg

Osteichthyes eggs are

spherical shaped with yolk for nourishing embryo

Osteichthyes, some species

guard their eggs but most do not

Osteichthyes internal fertilization

ovoviviparous

Example of internal fert in

Osteichthyes

seahorses

Osteichthyes seahorses

female lays eggs in males pouch, embryo dev within egg inside his pouch