CHAPTER 26 Sponges, Cnidarians, Flatworms, and Roundworms

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

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.

Sponge Reproduction

SpermSpermcellscells

LarvaeLarvae

EggEggcellcell

FlagellaFlagella

New spongeNew sponge

Sponges

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

Phylum Cnidaria and Cnetophora 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

Cavity

Bud

Disc Outer cell layer

Jellylike layer

Inner cell layer

Tentacle

Mouth

Has one body opening made of two layers of cells

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

Reproduction in Cnidarians

Reproduction: Sexually and asexually through budding

Review Questions

1. What type of symmetry do cnidarians have?

Radial2. 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

Phylum Platyhelminthes “Flatworms”

Characteristics Simplest animal with bilateral symmetry;

have long, thin flat bodies. Usually hermaphroditic.

Many are parasitic (ex: tapeworms, liver flukes)

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!)

Flatworms

Life Cycle of a Flatworm

Adult flukesAdult flukes

Embryos Embryos releasedreleased

LarvaLarva

Snail hostSnail host

LarvaLarva

Human Human hosthost

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

Phylum Nematoda “Roundworms” and Rotifera

Reproduction Most have separate sexes. Lay eggs.

Hookworm infections are common in Hookworm infections are common in humans in warm climates where they humans in warm climates where they walk on contaminated soil in bare feet.walk on contaminated soil in bare feet.

FYI: Roundworm parasites of FYI: Roundworm parasites of humanshumans

Hookworms cause Hookworms cause people to feel weak and people to feel weak and tired due to blood loss.tired due to blood loss.

Pinworms are the most common human Pinworms are the most common human roundworm parasites in the United States.roundworm parasites in the United States.

FYI: Roundworm parasites of FYI: Roundworm parasites of humanshumans

Pinworms are highly contagious because eggs Pinworms are highly contagious because eggs can survive for up to two weeks on surfaces.can survive for up to two weeks on surfaces.

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.

Phylum: ANNELIDA ANNELIDA “Segmented worms”“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.

Description: (PG.16 Purple Sheet)

Bilateral symmetry, segmented body, closed circulation (have vessels) and true digestive system, oxygen diffuses through skin

Phylum: ANNELIDA ANNELIDA “Segmented worms”“Segmented worms”

CHARACTERISTICS:Body Temp - Ectothermic

Symmetry - Bilateral Digestive System –

CompleteSkeletal System – None

Circulatory System – Closed

Reproductive System – Sexual

Heart Chambers – Heart Body

Earthworm

Leeches

Mollusks• 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!

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

Phylum: MOLLUSCAMOLLUSCA

CHARACTERISTICS:

Ectothermic Symmetry - BilateralDigestive System –

CompleteSkeletal System – None

Circulatory System – *OPEN*

Reproductive System – Sexual

Nervous System - SimpleHeart Chambers - 2 or

3 in some

Squid

Nautilus octopus

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

Arthropods

Phylum: ARTHROPODA ARTHROPODA “Arthropods”“Arthropods”

Crabs

Bull Ant

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 ARTHROPODA “Arthropods”“Arthropods”

Crabs

Bull Ant

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

- 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

• Many have camouflage to blend in with surroundings

Locust molting

Lobster

“Evil” Butterflies

CHARACTERISTICS:

Body Temp - Ectothermic

Symmetry - BilateralDigestive System –

CompleteSkeletal System –

ExoskeletonCirculatory System –

OpenReproductive System –

Very diverseNervous System -

SimpleHeart Chambers –

Muscular Tube

A termite mound made by the cathedral termite

The Arachnids: Ticks & Mites

Tick American House Mites

Egyptian Sea Star Sand Dollars

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

Spiny Cushion Sea Star

Phylum: Echinodermata Echinodermata “Echinoderms”“Echinoderms”

CHARACTERISTICS:

Body Temp - Ectothermic

Symmetry - Radial Digestive System –

CompleteSkeletal System –

ExoskeletonCirculatory System –

OpenReproductive System –

Sexual & asexualHeart Chambers – No true

heart