Agnatha

1. Name a vertebrate that has no jaws.Name a vertebrate that has no jaws.
There are only a few. There are only a few.
Evidence supports, jaws evolved from gill arches Evidence supports, jaws evolved from gill arches
in fish.in fish.
What would be the benefit to having jaws?What would be the benefit to having jaws?
Hold food,Hold food,
Food can’t escape stomachFood can’t escape stomach
Paired fins came at about the same time.Paired fins came at about the same time.
Imagine trying to swim with no front finsImagine trying to swim with no front fins

2. Class AgnathaClass Agnatha
VideoVideo

3. The only jawless fish left – and there are The only jawless fish left – and there are
80 Species of them80 Species of them
Lampreys and hagfishLampreys and hagfish
HagfishHagfish
Eyes beneath the skin,Eyes beneath the skin,
Have no vertebraeHave no vertebrae

4. Eat small invertebratesEat small invertebrates
Eat dead organismsEat dead organisms
Bottom dwellingBottom dwelling
Sometimes the burrow into the dead organisms and live Sometimes the burrow into the dead organisms and live
inside eating the organs.inside eating the organs.
They can tie themselves in knots and release a They can tie themselves in knots and release a
slime to get away from predators. slime to get away from predators.

5. Hagfish reproductionHagfish reproduction
Not much is knownNot much is known
Will lay 20 – 30 eggsWill lay 20 – 30 eggs
Can have couple of different batches of eggs Can have couple of different batches of eggs
inside female.inside female.
Some hermaphrodites have been found.Some hermaphrodites have been found.

6. Hagfish defense. – Eating, tying in knots, Hagfish defense. – Eating, tying in knots,
SL part 4 min 1.01SL part 4 min 1.01
Sea cucumber defense–SL part 2 min Sea cucumber defense–SL part 2 min
7.427.42

7. LampreysLampreys
Eel like in body structureEel like in body structure
Have large eyesHave large eyes
Many live in freshwaterMany live in freshwater
All reproduce in All reproduce in
freshwaterfreshwater
Some are free livingSome are free living
Some attach to hosts as Some attach to hosts as
parasites.parasites.
Some never eat as adults.Some never eat as adults.

9. ReproductionReproduction
Males make a craterMales make a crater
Females deposit the Females deposit the
eggs,eggs,
Males fertilize the Males fertilize the
eggseggs
Video clipVideo clip