Invertebrates

Chapter 29 and 30

Sponges, Cnidarians, Flatworms, Roundworms, mollusks, annelids

Animal Kingdom Characteristics

- multicellular

- eukaryotic

- heterotrophs

- movement

- tissues

Body Plans

- Bilateral Symmetry- equal halves in one direction

Radial Symmetry

• - 360 degrees; equal halves

- Asymmetry- cannot cut in equal halves

Body Development

- Ectoderm- outside body layer- skin and hair

- Endoderm- inside body layer- digestive tract

- Mesoderm-

middle layer- muscles, blood and organs

- Types of Body Cavities:

1. Coelom- true body cavity

- surrounded by mesoderm

-2. Pseudocoelom- false cavity

- between mesoderm and endoderm

3. Acoelomate

No body cavity.

Let’s Review.

What type of symmetry is this?

What type of symmetry?

Symmetry?

- Vertebrates- animals with backbones

- fish, amphibians, reptiles, birds, and mammals

- Invertebrates- animals without backbones

- sponges, cnidarians, mollusks, worms, echinoderms, arthropods

Sponges: Phylum PoriferaAsymmetrical – no symmetryNo tissues or organs (cells work together to perform a specific function2 body layers: endo-, ecto-Sessile – do not moveVariety of shapes and colorsAcoelemate – no body cavity

Variety of Sponges

                                       

Digestion of sponges

Sponges are consumers

Feed on bacteria, algae, protozoans (filter feeders)

Sponge digestion continued:

Reproduction

Either sexual or asexual

Asexual- fragmentation- each piece of sponge will grow into a complete new sponge

Sexual- hermaphrodite- produce both eggs and sperm- release into water at different times-sperm from one enters pores of other to fertilize eggs- External fertilization

Reproduction continued

Produces a zygote- free swimming larvae for a short time- attaches to surface- new sponge

Cnidarians- the stingersCoral

Characteristics of Cnidarians

Two Types: Polyp – sessile, tube-like

with tentacles ex. Coarl, sea anemone

Medusa – free swimming, umbrella shaped

Jellyfish

Has tissues – ecto-, endo-Nematocysts – stinging cells on tentaclesRadial symmetryacoelamate

B

How Cnidarians Get O2?

Diffusion

Have nervous tissue.

Reproduction

Asexual- budding- small extensions of body grow and then breaks away from parent

Sexual-some species are hermaphrodites Others, female releases egg and male releases

sperm into water- External fertilization

hydra

Portugese Man of War (colony)

Jelly fish

Sea anemone

Sea Anemones

Coral reef

Coral reefs

Structure

See diagram – oldest part is deeper. Newest is toward the top.

Live symbiotically with unicellular yellow brown algae- zooxanthellae

Benefit of Symbiotic Relationship:Coral gets:

food

(coral can also capture food with tentacles)

Algae gets:

Protection and access to sunlight

Coral Bleaching

When coral ejects it’s algae- coral turns white

Coral doesn’t get enough food- dies

Coral bleaching due to:

Diseases

Increased Ultra violet radiation

Sedimentation

Pollution

Increased water temperatures

Direct destruction by humans- anchors, touching while diving

Bleached coral

Flatworms

Acoelomate

Bilateral symmetry

Platyhelminthes – flatworms

Characteristics of flatworms:

Can be parasitic, or free living

1 body opening

Hermaphrodites or asexual reproduction by regeneration: breaking in 2, and each becomes a new organism

Get O2 through skin- diffusion

Tapeworm

Body Two parts: Scolex – head Proglottids – body

sections

Attach to inside of intestinesParasiteEx. Beef tapeworm: become infected by eating raw beef.

Getting Beef tapeworm:

Blood fluke - causes Schitomiasis

Planeria

Eyespots- light

Pharynx- extends like a straw, releases enzymes- breaks down food , sucks it up

Sensory pits on side of head, detect food, chemicals, and movement

Ability to regenerate

planeria

29-4 Roundworms

Pseudocoelum

Tube within a tube body

2 body openings

Move in a side to side manner

parasites

Ex. Ascaris - hookworm

Carried through human waste to soilIf ingested eggs enter large intestine – becomes larvaeLarvae bore through blood vesselsBack to the intestine to mate

Ascaris in pig intestine

Trichinella – pork roundworm

Causes Trichinosis

Eating improperly cooked pork

                                                                                                                    

Lymphatic Filariasis

                                                                                  

Mollusks and Annelids

Chapter 30

Mollusks

Characteristics Invertebrates Larval stage Marine, freshwater,

terristrial coelomates

Mollusks have 3 parts to body:

Visceral mass – contains organs

Mantle – tissue around visceral mass (secretes a shell)

Foot - locomotion

Other Mollusk characteristics:

Exoskeleton Sometimes called a

valve

Outer skeleton

•Radula

(not in bivalves)

Tongue-like structure

Organ systems of mollusks:

Excretory – get rid of waste:

Open Circulatory System –heart pumps fluid through a series of vessels out into body cavity

Organ Systems of Mollusks

Reproduction – most have separate sexes, external fertilization

Respiration – use gills

30-2 Groups of Mollusks

Bivalves – “two valves”

Valves held together by strong muscles

No radula

Filter feeders

Examples: clams, oysters, scallops

Bivalve Photos

Gastropods

Examples are snails and slugs

Single shell or none

Use radula to scrape food off of rocks etc

Land snails – hermaphrodites, aquatic snails – separate sexes

Herbivores

Gills or lungs?

Cephalopods – “head footed”

Examples: squid, octopusLarge head with tentaclesEyesMarine predators (consumers)Ink sac – for protectionInternal shell – penBrain present – complexSkin can change colorgills

Phylum Annelida

Segmented worms

Examples: earthworms, leeches, sandworms

Segmented body

Coelum

Bilateral symmetry

Abundant in all habitats

Organ Systems in Segmented Worms

Closed circulatory system

Excretory system – nephridia

Breath through skin

Bristles – setae

Reproduction – hermaphrodites

Digestion of Earthworm

Pathway of food: Pharynx – soil enters Esophagus - Crop-storage Gizzard- muscular for

grinding soil Intestines – absorption anus

Groups of Annelids

Marine segmented worms

Leeches