? There are sounds which are created on the mainland side of a barrier island.
? They consist of brackish water that is
created by rivers flowing into them from the mainland, and by seawater
that flows towards the land.
? The salinity (on the sound side) and the wave
action (on the outside of the barrier island) make different marine
environments and cause different organisms to be found.
? This coastline has no bedrock, and there are few rocky intertidal areas, most of which are manmade (i.e. jetties, sea walls, and bridges).
? Here there isnt a big difference between
high tide and low tide.
? Success-
being extant, and not extinct. An animal is successful or not
depending on its options.
? For example, a sponge has less options than a
squid, but they both, along with other animals, have a lot in common.
? For example, water balance, removal of
wastes, and reproduction.
? Marine invertebrates have different problems
than freshwater invertebrates.
? Complicated behavior can only be seen if the organism has a complicated morphology, and or physiology.
? For example, a crab has more complicated
behavior than a sponge because it has more complicated morphology and
physiology than the sponge.
Reproduction
? Seawater is better for external fertilization than freshwater is, and even better than the land is because the eggs and sperm are more like the seawater that they are in.
? The animals that release their gametes into the water are dieous, and this describes most of the marine invertebrates.
? Some marine invertebrates have internal fertilization such as cephalopods.
? There is internal fertilization where there are stressful conditions such as a constant salinity.
? In the estuaries where the salinity fluctuates is where there is external fertilization.
Development
? Direct development- when a juvenile grows to be an adult but the difference between the juvenile and the adult is very small (i.e.
turtles and turtles young).
? Indirect development- when the young is very different from the
adult because of their larvae (i.e. a tadpole to a frog, a caterpillar to
a butterfly).
? It must involve a metamorphosis usually.
? In this type of development, there is a life
history, and the larvae may be planktonic and metamorphose into another
larvae before becoming an adult.
? Different organisms may have direct, or
indirect development, and this is one way of seeing relationships between
different groups or categories of animals.
Two Theories
? 1. Maybe all animals had different ancestors.
? This is called polyphyletic.
? 2. Maybe all animals had a common ancestor.
? This is called monophyletic.
? Evolution can be seen by seeing if an organism is polyphyletic or monophyletic, from the fossil record, or by tissue formation, or by physical, or biological means.
? Mesozoans probably had the same ancestors.
? No one knows which one gave rise to multi celled organisms.
? Fossils, biochemistry, and developmental biology are different ways of trying to find out what gave rise to what.
Basic Marine Ecology
? The intertidal region has tides that come in (which are not exposed to the air) and tides that come out (which are exposed to the air).
? Semidiurnal- the tide increases and decreases twice everyday.
? Spring tide- when the moon is new or full which creates a high tide.
? Neap tide- when the moon is at half or quarter phase.
? Subtidal organisms are never exposed to air.
