Simple Invertebrates

1
Simple Invertebrates

• Sponges, jellyfishes and coral, flatworms,
  roundworms, and segmented worms too!

2
So what do you know about simple invertebrates?

• Do you know the main characteristics of each of
  the five phyla?
• Lets check them out.

3
Phylum Porifera(Sponges)

• Simplest animals of all (some of the oldest too).
• All are aquatic (freshwater and marine).
• Only two layers of cells, but no tissues or
  organs!
• Their skeletons are made of tiny spines called
  spicules.
• Cannot move (grow attached to the bottom).
• Mostly filter feeders.
• Uses?

4
The mighty sponge!
5
Phylum Cnidaria (aka Coelenterata) Jellyfishes
and Corals

• More advanced than sponges. (for example, they
  have tissues, but still no organs).
• Their body is a hollow cavity with only one
  opening (for food AND wastes)!
• Entirely aquatic (freshwater and marine).
• All have stinging cells, but not all can harm
  people.
• Some are pretty nasty predators. Others
  filter-feed on small particles and organisms in
  the water.

6
Medusae vs. Polyps

• MEDUSAE
• Ex. Jellyfishes.
• A medusa is free-swimming.
• Most are solitary.
• Their opening is on the bottom of their body.

• POLYPS
• Ex. Corals
• Polyps are like an upside down medusa.
• Their opening is on the top of their body.
• Coral polyps are tiny and live in huge colonies
  of thousands.
• Corals build their home as the colony grows
  larger and larger.

7
Jellyfish

• Most jellyfish are harmless to people, although
  not so to small fish and other marine organims.

8
Portuguese man-of-war.Look out!
9
Corals beautiful colonies of polyps.
10
A close-up of coral, shows how they are really
huge colonies of polyps upside down jellyfish
living in a stone apartments they build
themselves!
11
More Cnidarians hydra and sea anemones.Is it a
medusa or a polyp?
12
Not to confuse you, but did you know that
jellyfish start their lives as polyps, but become
medusae as an adult? Its true! Here is a
jellyfish life cycle.
13
Phylum Platyhelminthes(Flatworms)

• Even more complex.
• Long, flat body.
• Clearly defined head with mouth.
• Some have senses, a few even have eyespots.
• Some move freely.
• Many are parasites (ex. Tapeworm).
• Some live in the water (fresh or marine), others
  live inside their host!

14
Flatworms
15
Phylum Nematoda(Roundworms)

• Another step up the ladder!
• Some even have a simple nervous system.
• Some have a digestive system that runs through
  the entire body -- with two openings, one for
  food to enter and one for wastes to leave.
• Most are parasites.
• Many are harmless microscopic critters that live
  in the soil.
• Also, the trichina worm (in pork), as well as
  hookworms and heartworms (common in pets).

16
Roundworms!

• One teaspoon of garden soil may contain as many
  as 10,000 tiny nematodes (roundworms) in it!

17
Phylum Annelida(Segmented Worms)

• Most complex worms of all.
• Tube-like body divided into segments.
• Sophisticated digestive system! (mouth, crop and
  gizzard, intestine, anus)
• Many other specialized organs heart, blood
  vessels, nerve cords, simple brains)
• Can move well.
• Some aquatic (leeches, clam worms), some
  terrestrial (earthworms).
• Some are parasites (leeches), others are very
  important decomposers (earthworms).
• Any other uses for annelids?

18
Phylum Annelida(Segmented Worms)
19
Medicinal Leeches one way they are useful
annelids!(Click for video 800)
http//www.youtube.com/watch?vwl7REIufCtE
20
So NOW what do you know about the simple
invertebrates?

• Do you know the names of the five phyla of simple
  invertebrates?
• Do you know the main characteristics of each of
  the five phyla?
• Can you identify examples of animals in each of
  the five phyla?