18.5 - Invertebrate groups Flashcards
Symmetry: No Symmetry (Asymmetrical)
Number of Tissue Layers: None (no true tissues).
Coelom Type: Absent (acoelomate).
Digestive System: Intracellular digestion (no complete digestive tract).
Unique Features: Spongy Appearance: Poriferans (sponges) have a spongy texture. Regeneration: Sponges can regenerate lost body parts. Sessile, they don’t move.
Reproduction: Asexual and Sexually
No circulatory system
Examples: Sponges (e.g., Hydra, jellyfish medusae, and some corals
Porifera - Sponges
Symmetry: Radial
Number of Tissue Layers: Diploblastic (develop from two embryonic layers).
Coelom Type: Absent (acoelomate).
Digestive System: Incomplete (gastrovascular cavity).
Unique Features: Cnidocytes: Specialized stinging cells containing nematocysts (used for prey capture).
Polyp (Sessile) and Medusa (free-floating) Forms: Two distinct body plans.
Reproduction: Sexual and Asexual
No circulatory system
Examples: Polyp Form: Hydra spp. - Sessile they don’t move Medusa Form: Jellyfish (jellies) free-floating in the environment
Cnidaria - Jelly Fish & Sea anemones
Symmetry: Bilateral.
Number of Tissue Layers: Three (triploblastic).
Coelom Type: Absent (acoelomate).
Digestive System: Incomplete (gastrovascular cavity).
Unique Features: Chaetae: Chitinous bristles in each segment.
Clitellum: Structure for mucus production and cocoon formation.
Reproduction - Asexual (most) and Sexual
No circulatory system
Examples: Earthworms, leeches, and tapeworms.
Platyhelminthes - Flatworms
Symmetry: Bilateral
Number of Tissue Layers: Three (triploblastic).
Coelom Type: Pseudocoelom.
Digestive System: Complete (one-way tube from mouth to anus).
Unique Features: Ecdysis: Shedding of exoskeleton for growth.
Parasitic Adaptations: Can live in the digestive tract of chordates.
Have a cuticle to prevent them from drying out.
Reproduction - Sexual (Most) and Asexual
No circulatory system
Examples: Hookworms.
Nematoda - Roundworms
Symmetry: Bilateral.
Number of Tissue Layers: Three (triploblastic).
Coelom Type: True coelom (eucoelomate).
Digestive System: Complete (mouth to anus).
Unique Features: Metamerism: Segmentation of body.
Clitellum: Mucus production and cocoon formation.
Reproduction - Sexually
Closed Circulatory System
Examples: Earthworms, leeches
Annelida - Segmented worms
Symmetry: Bilateral.
Number of Tissue Layers: Three (triploblastic).
Coelom Type: True coelom (eucoelomate).
Digestive System: Complete (mouth to anus).
Unique Features: Mantle and Shell: Mollusks have a soft body covered by a calcium carbonate shell secreted by the mantle.
Radula: A specialized feeding organ with rows of tiny teeth.
Foot: A muscular structure used for locomotion.
Circulatory System: Most have an open circulatory
system with a heart, blood vessels, and hemolymph (a fluid similar to blood).
Reproductive - Sexual Reproduction
Examples: Gastropods: Snails, slugs. Bivalves: Clams, oysters, mussels. Cephalopods: Octopuses, squids, nautiluses
Mollusca
Symmetry: Bilateral.
Number of Tissue Layers: Three (triploblastic).
Coelom Type: True coelom (eucoelomate).
Digestive System: Complete (mouth to anus).
Unique Features: Exoskeleton: A hard, jointed covering made of chitin. Segmentation: The body is divided into segments with paired jointed appendages. Variety of Adaptations: Arthropods are found in diverse habitats and include insects, spiders, crustaceans, and more.
Circulatory System: Most have an open circulatory system with a dorsal heart, hemocoel, and hemolymph.
Reproductive: Sexual Reproduction
Examples:
Insects: Ants, dragonflies, bees.
Arachnids: Spiders, scorpions.
Crustaceans: Lobsters, crabs, shrimp.
Myriapods: Centipedes, millipedes
Arthropods - Jointed Legs
Symmetry: Adults - Radial / Larval - Bilateral
Number of Tissue Layers: Three (triploblastic).
Coelom Type: True coelom (eucoelomate).
Digestive System: Complete (mouth to anus).
Unique Features:
Water Vascular System: A network of fluid-filled canals used for locomotion and feeding.
Endoskeleton: Calcareous plates or spines embedded in the skin.
Regeneration Ability: Can regenerate lost body parts.
Circulatory System: lack a true circulatory system.
Reproductive Style Sexual Reproduction
Examples:
Starfishes (Sea Stars): Pentaradial symmetry, tube feet for locomotion.
Sea Urchins: Globular with spines.
Sea Cucumbers: Elongated, soft-bodied.
Brittle Stars: Long, flexible arms.
Sea Lilies: Sessile filter feeders
Echinoderms
Symmetry: Bilateral.
Number of Tissue Layers: Three (triploblastic)
Coelom Type: True coelom (eucoelomate).
Digestive Tract: Complete (mouth to anus).
Unique Features:
Notochord: A flexible rod-like structure extending into the head.
Dorsal Hollow Nerve Cord: Runs along the back and develops into the central nervous system.
Pharyngeal Slits: Used for feeding and gas exchange.
Post-Anal Tail: Extends beyond the anus.
Circulatory System; Lack a true circulatory system.
Reproductive Style: Sexual Reproduction
Examples:
Lancelets (Branchiostoma): Small, fish-like marine animals that burrow in sand and filter-feed using pharyngeal slit
Chordate (Invertebrate) - Lancelets
Symmetry: Bilateral
Number of Tissue Layers: Three (triploblastic).
Coelom Type: Reduced coelom (pseudocoelomate in larvae, but lost in adults).
Digestive Tract:
Larvae: Complete digestive tract (mouth to anus).
Adults: Reduced digestive system due to sessile filter-feeding lifestyle.
Unique Features:
Tunic: A tough outer covering made of cellulose-like material.
Filter Feeding: Tunicates use their pharyngeal slits for filter feeding.
Larval Notochord: Present in the larval stage but lost in adults.
Circulatory System: Have a simple circulatory system with a heart and blood vessels.
Reproductive Style:
Sexual Reproduction: Are hermaphroditic (both male and female organs in the same individual).
External Fertilization: Eggs and sperm are released into the water for fertilization.
Examples:
Sea Squirts (Ascidiacea): Sessile filter feeders attached to rocks or other surfaces.
Larval Tunicates: Exhibit all chordate characteristics but lose them during metamorphosis into adults
Chordate (Invertebrate) - Tunicates
