Invertebrates Flashcards
(23 cards)
What are the key characteristics of sponges? (5)
Simple, sessile animals that do not move as adults.
Lack true tissues or organs, but have specialized cells.
Can reproduce both sexually and asexually.
Asexually, they can reproduce through fragmentation or gemmules.
Can regenerate even from individual cells.
What are the main structural features of a sponge? (7)
Spongocoel: The central cavity of the sponge.
Osculum: The large opening where water exits the sponge.
Mesophyll: Jelly-like layer made of collagen and specialized cells.
Amoebocytes: Stem cells found in the mesophyll, involved in digestion and regeneration.
Choanocytes: Flagellated cells that line the spongocoel and create water currents to capture food.
Sclerocytes: Cells that produce spicules for structural support.
Pinacocytes: Flat outer cells that protect and regulate water flow.
How do sponges digest food?
Sponges have intracellular digestion. Choanocytes filter food particles from the water that flows through the sponge’s body. The food is then digested within individual cells.
How do sponges move?
Sponges are mostly sessile, meaning they do not move. However, they can move slowly by using crawling cells (pinacocytes) or spicules to shift their position. They may move for better access to food, avoiding harsh conditions, or dispersing after reproduction.
What are the key characteristics of cnidarians? (4)
Cnidarians are diploblasts (have two germ layers: ectoderm and endoderm).
They exhibit biradial symmetry (two planes of symmetry).
They have specialized stinging cells called cnidocytes for defense and capturing prey.
They have a nerve net for basic movement and response, but lack a brain.
What are the two main body forms in cnidarians?
Polyp: Stationary, vase-shaped body (e.g., corals, sea anemones).
Medusa: Free-swimming, umbrella-shaped body (e.g., jellyfish).
What are the main classes of Cnidaria? (4)
Anthozoa: Corals, sea anemones, and sea pens (always in the polyp form).
Scyphozoa: Jellyfish (mostly in the medusa form).
Cubozoa: Box jellyfish (known for being small and highly venomous).
Hydrozoa: Include tiny species like hydra and some freshwater species.
What are the defining features of Lophotrochozoa? (4)
Triploblasts: Three germ layers (ectoderm, endoderm, and mesoderm).
Bilateral symmetry: Left and right sides are mirror images.
Protostomes: The mouth develops first during embryonic development.
Cephalization: The development of a head region with sensory organs.
What are the characteristics of flatworms? (4)
They have a simple, flat body with no body cavity.
Flame cells are specialized excretory cells for osmoregulation and waste removal.
They are mostly parasitic, including classes like Cestoda (tapeworms), Trematoda (flukes), and Monogenea (ectoparasites).
Some are free-living like Turbellaria, long, soil-dwelling worms with a hammer-shaped head.
What are the characteristics of rotifers? (5)
Tiny animals with a complete digestive system.
Use a corona (cilia crown) for both feeding and movement.
They are pseudocoelomates, meaning their body cavity is not fully lined by mesoderm.
They possess a mastax, a throat with a false jaw for feeding.
The body is divided into three sections.
What are the characteristics of ribbon worms? (5)
Soft, unsegmented bodies with a long, extendable feeding tube called a proboscis.
They have contractile properties like a frog tongue.
Their body contains a rhynchocoel, a fluid-filled cavity.
They possess protonephridia, which are primitive excretory structures.
They also have a “brain” and hemoglobin to carry oxygen.
What are the defining features of mollusks? (5)
Visceral mass: Contains the internal organs.
Mantle: Often secretes a shell.
Radula: A toothed tongue for feeding (in most species).
Foot: Used for movement.
Hemocoel: A body cavity filled with fluid to transport blood and oxygen.
What are the major groups within Mollusca? (3)
Gastropods: Snails and slugs.
Cephalopods: Squid, octopus, and cuttlefish.
Bivalves: Clams, oysters, and mussels.
What are the key characteristics of segmented worms? (3)
The body is divided into segments (a feature called metamerism).
Setae are bristle-like structures that help with movement.
Annelids typically have a closed circulatory system (blood remains inside blood vessels).
What are the two main types of annelids?
Polychaetes: Have parapodia (paddle-like limbs).
Oligochaetes: Have a clitellum (used for reproduction), such as earthworms.
What are the key characteristics of Ecdysozoa? (3)
They are protostomes.
They exhibit bilateral symmetry and have three germ layers.
They undergo ecdysis, or molting, which means shedding their exoskeleton as they grow.
What are the characteristics of roundworms? (3)
Pseudocoelomates: Their body cavity is not fully lined by mesoderm.
Many are parasites.
Renette cells are specialized excretory cells that help with osmoregulation (maintaining water balance) and waste removal.
How do tardigrades survive extreme conditions?
Tardigrades can enter cryptobiosis, a state of suspended animation, to survive harsh conditions such as extreme heat, cold, and radiation.
What are the key characteristics of arthropods? (3)
They have a segmented body, jointed legs, and an exoskeleton.
The body cavity is called the hemocoel and it contains circulatory fluid.
Spiracles are openings in the exoskeleton that allow air to enter the respiratory system.
What are the major groups of arthropods? (4)
Chelicerates: Includes spiders, scorpions, and horseshoe crabs.
Myriapods: Includes millipedes and centipedes.
Crustaceans: Includes crabs, lobsters, shrimp, barnacles, and krill.
Hexapods: True insects with six legs and three body sections (head, thorax, abdomen).
What are the key features of Deuterostomes? (2)
They are triploblasts (having three germ layers).
The mouth forms second during development.
Major groups include Echinodermata and Chordata.
What are the key characteristics of echinoderms? (3)
Echinoderms have spiny skin and a water-based vascular system (ambulacral system) for movement and feeding.
They have tube feet for movement and gripping surfaces.
Hemal system is the circulatory system that moves nutrients around the body.
What are the main classes of Echinodermata? (4)
Asteroidea: Starfish.
Echinoidea: Sea urchins.
Holothuroidea: Sea cucumbers.
Ophiuroidea: Brittle stars.
