Invertebrates part 2

Flatoworms:

1. Type of symmetry: Flatworms have bilateral symmetry.

2. Animal phylum: Flatworms belong to the phylum Platyhelminthes.

3. Tissue layers: Flatworms have three tissue layers: ectoderm, mesoderm, and endoderm.

4. Nervous system: Flatworms have a simple nervous system with a pair of ganglia (nerve clusters) and two ventral nerve cords, allowing for basic movement and sensory processing.

5. Three classes of flatworms:

• Turbellaria: Free-living flatworms (e.g., planarians).

• Trematoda: Parasitic flukes.

• Cestoda: Parasitic tapeworms.

6. Parts and their function:

• Ganglia: Control center of the nervous system, similar to a brain.

• Eyespots: Light-sensitive structures that help detect light and dark.

• Pharynx: Muscular tube for feeding, extends to suck in food.

• Mouth: Opening for ingestion of food.

• Ventral nerve cord: Runs along the underside, transmitting signals.

• Gastrovascular cavity: Digestive cavity where food is broken down.

• Flame cells: Excretory cells that help remove waste and maintain water balance.

Roundworms:

1. Animal phylum: Roundworms belong to the phylum Nematoda.

2. Tissue layers: Roundworms have three tissue layers: ectoderm, mesoderm, and endoderm.

3. How they move: Roundworms move using a whip-like motion, facilitated by muscles along their body.

4. Differences and similarities of flatworms and roundworms digestive system

Similarities:

• Both have a digestive system that allows for the processing of food

Differences:

• Flatworms: Has a gastrovascular cavity with a single opening that serves as both mouth and anus.

• Roundworms: Have a more advanced complete digestive system with a separate mouth and anus.

5. Parts and their function:

• Mouth: Opening for food intake.

• Pharynx: Muscular tube that helps suck in food.

• Intestine: Digests food and absorbs nutrients.

• Anus: Opening for waste removal.

• Pseudocoelom: Fluid-filled body cavity that provides structure and helps with movement and nutrient transport.

Annelid Worms

1. Labeling: Annelid worms have an anterior end (head) and a posterior end (tail)

2. Type of symmetry: Annelids have bilateral symmetry.

3. Animal phylum: Annelid worms belong to the phylum Annelida.

4. How they move: Annelids move using longitudinal and circular muscles in their segments, often aided by setae.

5. Circulatory system: Annelids have a closed circulatory system with hearts (aortic arches) that pump blood through vessels.

   Organs:

   1. Dorsal Blood Vessel: Acts as a main heart, pumping blood forward.

   2. Ventral Blood Vessel: Carries blood back toward the rear.

   3. Segmental Vessels: Branch off to supply individual segments of the body.

   4. Capillaries: Tiny vessels where gas and nutrient exchange occurs.

6. Similarities and differences of annelids to flatworms and roundworms

   Similarities:

   • Multicellular: All three are multicellular organisms.

   • Bilateral Symmetry: They exhibit bilateral body symmetry.

   • Gastrointestinal Tract: Each has a digestive system for processing food.

   Differences:

   • Body Structure:

   • Annelids: Have a segmented body and a true coelom.

   • Flatworms: Are unsegmented with aacoelomate body plan.

   • Roundworms: Have a pseudocoelom and are also unsegmented.

   • Circulatory System:

   • Annelids: Have a closed circulatory system.

   • Flatworms: Lack a circulatory system

   • Roundworms: Also lack a circulatory system

7. Parts and their function:

• Mouth: Opening for food intake.

• Pharynx: Muscular tube for feeding.

• Crop: Storage area for food.

• Gizzard: Grinds food.

• Intestine: Digests food and absorbs nutrients.

• Anus: Waste removal.

• Nephridia: Excretory organs that remove waste.

• Septum: Divides body segments.

• Aortic arches: Pump blood.

• Clitellum: Secretes mucus for reproduction.

• Ventral nerve cord: Transmits nerve signals.

Mollusks

1. Type of symmetry: Mollusks have bilateral symmetry.

2. Animal phylum: Mollusks belong to the phylum Mollusca.

3. Body plan: Mollusks have four main parts: foot, visceral mass, mantle, and shell.

4. Circulatory system: Mollusks typically have an open circulatory system (except cephalopods), where blood flows in sinuses.

5. How they move: Mollusks move using a muscular foot, which can be adapted for crawling, burrowing, or jet propulsion (in cephalopods).

6. Radula use: The radula is a tongue-like structure used for scraping food; its shape varies based on diet (e.g., herbivores vs. carnivores).

7. Respiration differences: Aquatic mollusks typically use gills, while terrestrial mollusks have a lung-like structure for gas exchange.

8. Comparison of octopuses and simple mollusks:

• Circulatory system: Octopuses have a closed circulatory system; simple mollusks have an open system.

• Movement: Octopuses use jet propulsion; simple mollusks crawl.

• Nervous system: Octopuses have a complex, centralized nervous system; simple mollusks have a simpler nerve network.

9. Three classes of mollusks:

• Gastropoda: Snails and slugs; often have a coiled shell.

• Bivalvia: Clams and oysters; two-part shell.

• Cephalopoda: Squid and octopuses; complex brains and tentacles.

10. Parts and their function:

• Foot: Muscular structure for movement.

• Visceral mass: Contains internal organs.

• Mantle: Tissue covering the body; secretes the shell.

• Shell: Protective outer layer (if present).

• Radula: Scraping organ for feeding.

• Siphon: Tube for expelling water, aiding in movement.

• Mantle cavity: Houses gills and excretory organs.

• Sinuses: Spaces for blood flow in an open circulatory system.

• Nephridia: Excretory organs that remove waste.

• Trochophore: Larva stage of some mollusks.

Arthropods

1. Type of symmetry: Arthropods have bilateral symmetry.

2. Animal phylum: Arthropods belong to the phylum Arthropoda.

3. Three characteristics:

• Exoskeleton made of chitin.

• Segmented body.

• Jointed appendages.

4. Three main parts of an insect:

• Head

• Thorax

• Abdomen

5. Three respiratory structures:

• Gills (aquatic).

• Tracheal tubes (terrestrial).

• Book gills/lungs (some aquatic and terrestrial).

6. Circulatory system: Arthropods have an open circulatory system with hemolymph, while mollusks can have either an open or closed system.

7. Reproduction differences: Terrestrial arthropods often lay eggs on land, while aquatic arthropods lay eggs in water.

8. Metamorphosis stages:

• Incomplete metamorphosis: Egg → nymph → adult (e.g., grasshoppers).

• Complete metamorphosis: Egg → larva → pupa → adult (e.g., butterflies).

9. Difference between metamorphosis types: Incomplete has no distinct larval stage, while complete has a distinct pupa stage.

10. Parts and their function:

• Exoskeleton: Provides support and protection.

• Appendages: Aid in movement, feeding, and reproduction.

• Cephalothorax: Fused head and thorax in some arthropods.

• Gills: For respiration in aquatic arthropods.

• Tracheal tubes: For breathing in terrestrial arthropods.

• Book gills/lungs: Specialized structures for gas exchange.

• Malpighian tubules: Excretory structures that remove waste.

Echinoderms

1. Type of symmetry: Echinoderm larvae have bilateral symmetry; adults have radial symmetry.

2. Animal phylum: Echinoderms belong to the phylum Echinodermata.

3. Water vascular system: A network of fluid-filled canals used for locomotion, feeding, and gas exchange.

4. Feeding methods: Echinoderms can use tube feet to capture prey, evert their stomachs, or filter feed.

5. Different classes of echinoderms:

• Asteroidea (sea stars)

• Echinoidea (sea urchins)

• Ophiuroidea (brittle stars)

t• Holothuroidea (sea cucumbers)

• Crinoidea (feather stars)

6. Reproduction: Echinoderms typically reproduce sexually with external fertilization; some can regenerate lost parts.

7. Parts and their function:

• Tube feet: Used for movement and feeding.

• Water vascular system: Controls tube feet and aids in movement.

• Nerve ring: Coordinates nervous system activities.

• Eyespots: Light-sensitive structures that detect light.

• Skin gills: Used for respiration and excretion.