Invertebrates and Porifera: Sponges

Invertebrates

• Invertebrates are animals without backbones.
• 97% of the animal kingdom consists of invertebrates.
• They live in various environments, including ponds, oceans, and other water sources.
• Some invertebrates have exoskeletons, which are hard outer coverings that protect the animal's body and provide shape.

Porifera: Sponges

• Sponges live in water; most are found in the ocean.
• They resemble plants but are animals.
• Sponges are sessile, meaning they remain fixed in one place.
• Their bodies have many pores, and their skeletons are made of spiky fibers (spicules) or rubbery spongin.
• Sponges are categorized by the type of spicule they possess; there are approximately 5,000 identified species.
• Water flows through sponge pores, aided by flagella, which helps them capture food.
• Sponges reproduce asexually through budding or gemules. Gemules are structures that allow a new sponge to grow from pieces of an established one.
• Most sponges that reproduce sexually are hermaphrodites.
• Sperm released into water flows into another sponge, where fertilization occurs, enabling larva development inside the sponge.
• The larva is released and settles at the bottom, eventually growing into an adult sponge.

Cnidaria: Corals, Hydras, and Jellyfish

• The name Cnidaria originates from the Greek word for nettle.
• All cnidarians have stinging cells called nematocysts in their tentacles, which surround their mouths.
• Cnidarians are more complex than sponges, possessing complex tissues, a digestive tract, and a nervous system.
• They exist in two forms: polyp and medusa.
• Polyps are typically sessile and vase-shaped.
• Medusae are free-swimming and bell-shaped.
• Cnidarians reproduce both asexually (budding) and sexually.

Sea Anemones and Corals

• Sea anemones and corals are polyps throughout their entire life cycle.
• They look similar to brightly colored flowers.
• They live in colonies.
• Their bodies are soft and tube-like, with a single opening and numerous tentacles.

Hydras

• Hydras inhabit freshwater environments.
• They remain in the polyp stage throughout their life cycle.
• Hydras feature tentacles for capturing food.
• They are mobile.
• Hydras are small animals.
• They reproduce asexually through budding.

Jellyfish

• Jellyfish predominantly exist as medusae throughout their lives.
• They swim freely in the water.
• Jellyfish catch smaller animals (like shrimp, fish) using their tentacles.
• Reproduction is a two-stage process: they first reproduce sexually to create polyps, and then asexually to produce new medusae.

Platyhelminthes: Flatworms

• Flatworms are characterized by their flattened bodies, presence of a head and tail, and bilateral symmetry.
• Flatworms search for food using their long, flattened bodies.
• Some flatworms are free-living, such as Planaria.
• Tapeworms are parasitic flatworms.
• Each segment of a tapeworm (proglottid) contains reproductive organs, and when fertilized eggs fill a segment, it detaches and exits the host's waste.
• Tapeworms can contain tens of thousands of eggs in a single segment.
• They lack a digestive system, obtaining nutrients from the host's intestines.

Nematoda: Roundworms

• Roundworms have rounded, tube-like bodies.
• Their digestive tract has both a mouth and an anus.
• They live in damp environments or inside humans and other animals.
• Some roundworms are heartworms, passed to their host through mosquito bites.
• They can also cause other illnesses to both humans and other animals.
• Roundworms can be decomposer worms, predatory worms, or parasitic worms.
• There are billions of roundworms in just one acre of soil.

Annelida: Segmented Worms

• Annelids include earthworms, leeches, and marine worms.
• Their bodies are divided into repeating segments.
• Each segment contains nerve cells, blood vessels, and part of their digestive tract.
• They have a closed circulatory system and a complete digestive system with two openings.
• Earthworms have more than 100 body segments and use external bristles (setae) and muscles for locomotion.
• They consume organic matter in the soil.
• They exchange gases (CO2 and O2) through their mucus-covered skin.

Mollusca: Snails, Slugs, Clams, and Squid

• Mollusks possess a soft body often covered in a hard shell.
• They have a rough tongue called a radula and a muscular foot, as well as a mantle that produces the shell.
• Aquatic mollusks use gills for gas exchange, while land mollusks have lungs.
• Snails have one shell, while clams have two shells held together by a hinge.

Gastropod Mollusks: Slugs and Snails

• Most gastropods have one shell.
• They live in water or on land.
• Gastropods move by gliding their muscular feet along a mucus trail.

Bivalve Mollusks: Clams and Other Two-Shelled Shellfish

• Bivalves have two shells.
• Large muscles open and close the halves of the two shells.
• Bivalves are water animals that filter feed.
• They use gills to remove food from water.

Cephalopod Mollusks: Octopus and Squid

• Cephalopods lack an external shell.
• Their foot is divided into tentacles with suckers.
• They move by squeezing water through a funnel-like siphon.
• They have a closed circulatory system with blood vessels.

Arthropoda: Insects, Spiders, Millipedes, and Crustaceans

• Arthropods are invertebrates with jointed appendages (like legs and claws), antennae, and a hard exoskeleton.
• They have bilateral symmetry.
• There are over a million species of arthropods.
• Arthropods molt, or shed their exoskeleton, as they grow, allowing their bodies to continue growing.

Insects: Characteristics and Metamorphosis

• Insects have three body parts: head, thorax, and abdomen.
• The head has antennae and eyes.
• The thorax has legs and wings.
• Reproductive organs are located in the abdomen.
• Insects have an open circulatory system.
• Oxygen enters through the insect's body.
• Insects can undergo complete metamorphosis (egg, larva, pupa, adult), or incomplete metamorphosis (egg, nymph, adult).

Arachnids: Spiders, Scorpions, Ticks, and Mites

• Arachnids have two main body parts: a cephalothorax and an abdomen.
• The thorax has four pairs of jointed legs; arachnids do not have antennae.
• Arachnids have special mouthparts, such as fangs.
• Spiders kill more insect pests than any other animal.

Myriapods: Centipedes and Millipedes

• Centipedes use their many legs to run away from enemies.
• They have one pair of jointed legs on each segment.
• Centipedes are predators.
• Millipedes have two pairs of jointed legs on each segment.
• Millipedes roll up their bodies when threatened.
• They are herbivores.

Crustaceans: Shrimp, Crabs, Crayfish, and Lobsters

• Crustaceans are mostly aquatic (in water) and have gills.
• They have two pairs of antennae, three types of chewing appendages, and five pairs of legs.

Echinodermata: Starfish and Sea Urchins

• Echinoderms have tiny tube feet and body parts arranged around a central area.
• Starfish have five arms but no head.
• The hard, spiny covering of starfish and sea urchins provides protection.
• Sea urchins have spines covering their bodies.
• Echinoderms exhibit radial symmetry.
• They can be filter feeders, predators, or eat rotting materials.
• They have a water vascular system for movement and consumption of food.
• Some echinoderms can reproduce by regeneration from lost body parts.

Explore the fascinating world of invertebrates, which make up a significant portion of the animal kingdom. This quiz focuses on sponges, their unique characteristics, habitats, and reproductive methods. Dive into the details of this intriguing class of animals!