1. Sponges, Cnidarians, Flatworms, and Roundworms
Chapter 26
Sponges, Cnidarians, Flatworms, and Roundworms

2. Phylum Porifera (Sponges)
Characteristics:
Simple body structure with no true tissues; multicellular, (hermaphrodites—animal has both male and female structures), asymmetrical
Sessile—no movement as adults; are filter feeders (catch food as it floats through them)
Have pores that absorb water
Spicules—tiny hard particles of calcium or silicon compounds that make up skeleton

3. Phylum Porifera (Sponges)
Reproduction: can be asexual (budding) or sexual by releasing sperm that enters other sponges through pores where it will fertilize the egg.
After fertilization, larvae will develop. Larvae are immature stages of an animal.

4. Sponge Reproduction
Sperm
cells
Larvae
Egg
cell
Flagella
New sponge

5. Sponges

6. Review Questions
1. What word means that a sponge does not move? Sessile 2. How do sponges eat? By filtering the water around them 3. What tiny, hard particles make up the sponge skeleton? Spicules

7. Phylum Cnidaria and Cnetophora
Cavity
Bud
Disc
Outer cell layer
Jellylike layer
Inner cell layer
Tentacle
Mouth
Characteristics
Radial symmetry with true tissues; cup/bell shaped
Have stinging cells called nematocysts to help capture food
Sting can be fatal to humans
examples: hydra (very tiny jellyfish-like animal), jellyfish, coral, sea anemones
Has one body opening made of two layers of cells

8. Body Form of Cnidarians
Has 2 life forms during their life cycle:
Polyp- has a tube-shaped body with a mouth surrounded by tentacles.
Medusa- has an umbrella-shaped body called a bell.
Polyp
Medusa

9. Reproduction in Cnidarians
Reproduction: Sexually and asexually through budding

10. Review Questions
1. What type of symmetry do cnidarians have? Radial 2. What are nematocysts? Stinging cells 3. Give an example of a cnidarian. Coral, jellyfish, sea anemone, hydra 4. What are the 2 life forms of a cnidarian? Polyp & medusa

11. Phylum Platyhelminthes “Flatworms”
Characteristics
Simplest animal with bilateral symmetry; have long, thin flat bodies. Usually hermaphroditic.
Many are parasitic (ex: tapeworms, liver flukes)

12. Phylum Platyhelminthes “Flatworms”
Reproduction
Usually hermaphroditic and reproduce sexually. During mating, they fertilize each other at the same time.
Some can reproduce asexually by regenerating (regrowing) lost parts. (ex: cut planarian: will grow back lost parts!)

13. Flatworms

14. Life Cycle of a Flatworm
Adult flukes
Embryos
released
Larva
Snail host
Human
host

15. Phylum Nematoda “Roundworms” and Rotifera
Characteristics
Bilateral symmetry, have both mouth and anus
Live in soil, fresh and marine water.
Nematodes: roundworms that are often parasitic
Examples: Ascaria (intestinal roundworm about 1 ft long), hookworms, trichinella (from undercooked pork), pinworms, heartworms

16. Phylum Nematoda “Roundworms” and Rotifera
Reproduction
Most have separate sexes. Lay eggs.

17. FYI: Roundworm parasites of humans
Hookworm infections are common in humans in warm climates where they walk on contaminated soil in bare feet.
FYI: Roundworm parasites of humans
Hookworms cause people to feel weak and tired due to blood loss.

18. FYI: Roundworm parasites of humans
Pinworms are the most common human roundworm parasites in the United States.
Pinworms are highly contagious because eggs can survive for up to two weeks on surfaces.

19. FYI: Ascaris
Eggs of Ascaris are found in soil and enter a human’s body through the mouth.
Ascaris worm coming out of a pig.

20. Phylum: ANNELIDA “Segmented worms”
Beard worm
Christmas tree worm
- Also have: (turn to pink sheet)
Setae—external bristles for movement
Coelom—true fluid-filled body cavity
Ex: Earthworms, leeches
Earthworms loosen soil and make it better for growing plants
Reproduction
Sexual: hermaphrodites (have sperm and eggs), cannot fertilize themselves.
Phylum: ANNELIDA “Segmented worms”
Description: (PG.16 Purple Sheet)
Bilateral symmetry, segmented body, closed circulation (have vessels) and true digestive system, oxygen diffuses through skin

21. Phylum: ANNELIDA “Segmented worms”
CHARACTERISTICS:
Body Temp - Ectothermic
Symmetry - Bilateral
Digestive System – Complete
Skeletal System – None
Circulatory System – Closed
Reproductive System –
Sexual
Heart Chambers – Heart Body
Earthworm
Phylum: ANNELIDA “Segmented worms”
Leeches

22. Class Gastropoda (snails & slugs)…2nd largest class after Class Insecta
Class Bivalvia “Bivalves” (scallops, oysters, clams, mussels)
Class Cephalopoda (squid & octupi)…Only mollusks with brains!
Mollusks

23. *from Latin word, “molluscus” - soft
Phylum: MOLLUSCA
*from Latin word, “molluscus” - soft
Description:
*2ND Largest Phylum of Animals
3 Main Body Parts:
1. Muscular foot
2. Head
3. Visceral mass (its insides)
FYI: terrestrial and marine
Reproduction
Sexual: most have separate sexes, produce gametes
Giant clam
Sea Slug

24. Phylum: MOLLUSCA CHARACTERISTICS: Ectothermic Symmetry - Bilateral
Digestive System – Complete
Skeletal System – None
Circulatory System – *OPEN*
Reproductive System –
Sexual
Nervous System - Simple
Heart Chambers - 2 or 3 in some
Squid
Phylum: MOLLUSCA
Nautilus
octopus

25. Arthropods Subphylum Crustacea (lobsters, crabs, crayfish…GILLS)
Class Insecta (all insects have 6 legs)
Class Arachnida (spiders & scorpions…all have 8 legs)
Class Diplopoda (millipedes)
Class Chilopoda (centipedes)
Arthropods

26. Phylum: ARTHROPODA “Arthropods”
Crabs
Description:
Have segmented appendages (joints) that allow for flexibility
Molting—since exoskeletons do not grow, arthropods have to shed exoskeleton and form new one
Phylum: ARTHROPODA “Arthropods”
Bull Ant

27. Phylum: ARTHROPODA “Arthropods”
Crabs
Description:
Mandibles—mouthparts for holding, chewing, sucking, biting
Have segments fused into three main body sections: head, thorax, abdomen; a fusion of the head & thorax = cephalothorax
Phylum: ARTHROPODA “Arthropods”
Bull Ant

28. Oxygen obtained through: gills, tracheal tubes, or lungs
Metamorphosis—series of 4 changes in shape and body structure during development.
Incomplete metamorphosis— only has 3 stages; once such an insect hatches, it looks almost like the adult version and is called a nymph

29. Many have camouflage to blend in with surroundings

30. Body Temp - Ectothermic Symmetry - Bilateral
Locust molting
CHARACTERISTICS:
Body Temp - Ectothermic
Symmetry - Bilateral
Digestive System – Complete
Skeletal System – Exoskeleton
Circulatory System – Open
Reproductive System –
Very diverse
Nervous System - Simple
Heart Chambers – Muscular Tube
“Evil” Butterflies
Lobster

31. A termite mound made by the cathedral termite

32. The Arachnids: Ticks & Mites
American House Mites

33. Egyptian Sea Star Sand Dollars
Spiny Cushion Sea Star
Description:
Move with tube feet— appendages with suction cups on tips
FYI: Have mouth, stomach, intestines, but no head/brain
All echinoderms have exoskeletons made of calcium carbonate.
Reproduction
Sexually with gametes, asexually with regeneration
Feather
Star
Egyptian Sea Star Sand Dollars

34. Phylum: Echinodermata “Echinoderms”
CHARACTERISTICS:
Body Temp - Ectothermic
Symmetry - Radial
Digestive System – Complete
Skeletal System – Exoskeleton
Circulatory System – Open
Reproductive System –
Sexual & asexual
Heart Chambers – No true heart
Phylum: Echinodermata “Echinoderms”