Invertebrates and Marine Biology Lecture
Definition and Importance
- Invertebrates: Animals without vertebrae or a backbone.
- 97% of animals are invertebrates, particularly in marine environments.
- Include all major animal groups, often uniquely found in marine settings.
Characteristics of Animals
- Multicellular: Specialization of organs and tissues.
- Heterotrophic: Rely on consuming other organisms for energy.
- Aerobic respiration: Use oxygen with mitochondria for energy.
- Reproduction: Sexual, asexual, or both.
- Motility: Most animals move during their life cycle.
- Development: Unique embryonic development.
Animal Classification: Body Structure
- Symmetry:
- Radial: Circular symmetry (e.g., jellyfish).
- Pentaradial: Five-part symmetry (e.g., sea stars).
- Bilateral: Left and right halves.
- Asymmetry: No symmetry (e.g., sponges).
Marine Animal Phyla
- Sponges (Porifera)
- Simplest animals, no tissues, filter feeders.
- Asymmetrical, regenerative ability.
- Defense: Spicules and spongin.
- Reproduction: Sexual and asexual.
- Cnidarians
- Radial symmetry, medusa and polyp forms.
- Stinging cells (cnidocytes) with nematocysts.
- Includes jellyfish, corals, and sea anemones.
- Flatworms (Platyhelminthes)
- Parasites like flukes and tapeworms.
- Bilateral symmetry, simple nervous system.
- Free-living and parasitic varieties.
- Segmented Worms (Annelids)
- Segmented bodies, bilateral symmetry.
- Includes earthworms and marine polychaetes.
- Found in diverse habitats including hydrothermal vents.
- Mollusks
- Soft-bodied, with head, muscular foot, and mantle.
- Includes gastropods (snails), bivalves (clams), and cephalopods (octopi).
- Open circulatory system, various feeding strategies.
- Arthropods
- Exoskeleton made of chitin, jointed appendages.
- Includes crustaceans (crabs, shrimp) and insects.
- Echinoderms
- Pentaradial symmetry, spiny skin.
- Includes sea stars, sea urchins, and sea cucumbers.
- Water vascular system for movement.
- Chordates
- Six characteristics: notochord, nerve cord, gill slits, post-anal tail, pharynx, heart.
- Include tunicates and lancelets.
Key Concepts and Questions
- Animal Characteristics: Identify and differentiate.
- Symmetry Types: Examples and significance.
- Phyla Examples: Characteristics and representative species.
- Reproductive Strategies: Asexual and sexual reproduction in marine species.
Questions for Review and Quiz Preparation
- What are three characteristics of animals?
- What are the symmetries of a sea star, sponge, and flatworm?
- What are the flagellated cells of sponges called?
- What are the two stages of cnidarians?
- Which class do corals belong to?
- What type of flatworms have a scolex?
- Which group of annelids would you find in hydrothermal vents?
- Match the description with the mollusk groups.
- What is the carbohydrate in an arthropod exoskeleton?
- What does the word echinoderm mean?
These notes summarize the main points of the lecture on invertebrates, focusing on various marine animal phyla, their characteristics, and examples.