GB1 Lab Chapter 7 - Mollusks Quiz

Mollusks

• Characterized by a three-part body plan: foot, mantle, and visceral mass.
• Major groups include chitons, bivalves, gastropods, and cephalopods.
• Chitons are marine, have oval bodies and shells, and are generally sessile.
• Bivalves have two-part shells and siphons (examples: clams, scallops).
• Gastropods can be aquatic or terrestrial, with a flat foot and spiral shells (examples: snails and slugs).
• Cephalopods feature a cone-like mantle and modified foot-arms for movement (examples: squid, octopus).
• Siphons in squids play roles in locomotion, respiration, and waste discharge.
• Adductor muscles in clams operate the opening and closing of shells.
• Gills in both squids and clams are essential for gas exchange and respiration.
• Squids possess a radula for cutting prey, while clams use it for scraping food.
• Shells provide protection from predators, enhancing evolutionary success.
• Squid and octopus adaptations include tentacles for capturing prey, sharp beaks for consumption, and advanced color vision.
• Prominent sensory organs in cephalopods support their predatory and active lifestyles, enabling feeding, attacking prey, and reproduction.

Arthropods

• Distinguishing characteristics include segmented bodies, joined appendages, and exoskeletons composed of chitin.
• Bilateral symmetry is a common feature among arthropods.
• Similarities with annelids include external segmentation and muscle organization; differences lie in respiration and circulatory systems.
• Arthropods have segmented appendages, a chitinous cuticle, and an open circulatory system, while annelids have a closed circulatory system and collagenous cuticle.
• The exoskeleton serves as a protective outer covering, preventing injury and predation.
• Survival success attributed to their tough exoskeletons, enhancing defense mechanisms.

Cnidaria

• Cnidarians exhibit radial symmetry, possess tentacles, and are classified as diploblastic organisms.

Platyhelminthes

• Known as flatworms, they are triploblastic, acoelomate, bilaterally symmetrical, often parasitic, and have a flattened body structure.

Annelida

• Annelids feature bilateral symmetry, coelomate structure, a developed nervous system, segmented organs, and advanced circulatory and respiratory adaptations.

General Features of Animal Phyla

• Sponges (Porifera) are multicellular, lack true tissues and organs, and exhibit no symmetry.
• Arthropoda define themselves with an exoskeleton, segmented body structure, jointed appendages, bilateral symmetry, and an open circulatory system.
• Mollusca are characterized by soft bodies often protected by shells, bilateral symmetry, radula presence, mantle, and muscular foot.