Animal Kingdom Notes

Porifera (Sponges)

• Movement: Sessile (attached to a surface); filter water through pores.
• Support:
  • Spicules (hard, mineral).
  • Spongin (soft).
• Symmetry: Asymmetrical (no symmetry).
• Osculum: Excurrent opening for water.
• Diffusion: Sponges use diffusion for gas exchange (circulation & respiration).
• Nutrition/Digestion: Filter feeding through pores to bring in small animals.
• Collar cells: Cells with flagella that create a water current.
• Reproduction:
  • Asexual (budding).
  • Sexual (external fertilization).
  • Sponge larva grows spicules to form a new sponge.

Cnidaria (Jellyfish, Corals, Hydras)

• Digestion: Mouth and anus are the same opening, leading to the gastrovascular cavity where food is digested.
• Symmetry: Radial symmetry (same in many directions).
• Support:
  • Two germ layers.
  • Soft body, except for coral (stone skeleton).
• Nerves/Response:
  • Tentacles lined with nematocyst-containing cells (cnidocytes).
  • Nematocysts have poisonous barbs to sting prey.
• Movement:
  • All cnidarians begin life as a polyp (sessile form).
  • Some become mobile medusas (free-swimming form).
• Reproduction:
  • Asexual (budding in hydras).
  • Sexual (external fertilization).

Platyhelminthes (Flatworms)

• Body Protection: Bodies protected by a cuticle.
• Digestion: Muscular pharynx pulls food into the gastrovascular cavity.
• Nervous System: Two eyespots with two lateral nerve cords along sides of the worm and cephalization.
• Respiration: Diffusion.
• Excretion: Flame cells remove liquid waste.
• Symmetry: Bilateral (body has two distinct sides).
• Cephalization: Concentration of sensory organs in a head region.
• Movement: Free-living flatworms move with rhythmic muscular contractions.
• Reproduction:
  • Asexual (regeneration).
  • Sexual (hermaphroditic - possessing both male and female reproductive organs).

Nematoda (Roundworms)

• Body Protection: Bodies protected by a cuticle.
• Digestion: Food is sucked in by a muscular pharynx and absorbed in the intestines.
• Nervous System: Rings of nervous tissue around the pharynx; two long nerve cords; sensory organs concentrated in the head.
• Reproduction: Sexual with separate sexes; external fertilization.
• Circulation and Respiration: Diffusion.
• Parasitic Nature: Some flatworms and most roundworms are parasitic, feeding off a host organism.
• Movement: Often uncoordinated with frantic, thrashing motions.
• Excretion: Wastes excreted from excretory canals just below the mouth.

Annelida (Segmented Worms)

• Body Protection: Bodies protected by a cuticle.
• Movement: Two sets of muscles (circular & longitudinal) and setae for movement.
• Digestion: Pharynx, stomach, gizzard, & intestine; complete digestive system (mouth and anus).
• Nervous System: Ganglia in head connected to a ventral nerve cord & nerves.
• Circulatory System: Closed (blood contained in vessels).
• Respiration: Through their skin.
• Excretion: Nephridia remove wastes.
• Reproduction:
  • Some can regenerate.
  • Sexual reproduction.
  • Earthworms are hermaphroditic.

Mollusca (Snails, Clams, Squids)

• Body Organization:
  • Head.
  • Foot.
  • Visceral Mass.
  • Mantle.
• Shell: All mollusks have shells; some are external; some are internal.
• Symmetry: Bilateral symmetry (two distinct halves).
• Circulation: Open circulatory system (colorless blood; heart).
• Respiration: Two pairs of gills to draw oxygenated water into the mollusk.
• Excretion: One or two pairs of kidneys.
• Reproduction:
  • Sexes are separate.
  • Fertilization can be internal or external.
  • Larvae are called trochophores.
• Digestion: Alimentary canal (digestive tract) is well developed.
• Radula: Tongue for scraping vegetation.
• Nervous: Several paired sets of ganglia.
• Sensory organs: Complex and varied, including balance receptors, chemical receptors, and light and touch receptors.
• Examples:
  • Bivalvia (Scallops, clams, oysters).
  • Gastropoda (Snails).
  • Cephalopoda (Octopus, squid).

Echinodermata (Starfish, Sea Urchins, Sea Cucumbers)

• Meaning: "Spiny skinned".
• Movement: Slow-moving or sessile; use tube feet like suction cups.
• Symmetry: Radial symmetry around a central point.
• Nervous:
  • Network of nerves including eye spots on the ends of their arms.
  • Nerve cords run down each arm.
• Circulation & Respiration: Open circulatory system combined with a water vascular system.
• Water vascular system: water is pumped in and around the animal's body, aiding in circulation and gas exchange
• Support: Endoskeleton made of calcium carbonate.
• Digestion: Simple but complete digestive system with mouth and anus; some can turn stomachs inside out.
• Reproduction:
  • Eggs and sperm are released into the water.
  • External fertilization.
  • Some echinoderms have amazing regenerative properties.
• Examples:
  • Asteroidea (Sea stars).
  • Ophiuroidea (Brittle stars).
  • Holothuroidea (Sea cucumbers).
  • Echinoidea (Sea urchins, sand dollars).
  • Crinoidea (Sea lilies & feather stars).

Arthropoda (Insects, Crustaceans, Arachnids)

• Meaning: "Jointed foot".
• Largest Phylum of Animals!
• Symmetry: Bilateral.
• Support: Exoskeleton made of chitin; requires molting.
• Circulation: Open circulatory system; heart that bathes the organs in hemolymph (no blood vessels).
• Digestion: Complete digestive system (mouth, stomach, intestine, anus).
• Reproduction: Separate sexes; sperm is transferred to the female internally; eggs are fertilized as they are laid.

Crustacea (Crabs, Lobsters, Shrimp)

• Habitat: Mostly found in aquatic habitats.
• Body Organization:
  1. Cephalothorax
  2. Abdomen
• Specialized Structures:
  • Gills
  • Eyes on stalks
  • Green glands to filter liquid waste
• Number of Legs: Varies (2/segment).

Chelicerata (Spiders, Scorpions, Horseshoe Crabs)

• Named for: Special mouthparts called chelicerae (fangs).
• Body Organization:
  1. Cephalothorax
  2. Abdomen
• Specialized structures:
  • Book lungs for respiration.
  • No antennae.
  • Pedipalps for touch.
  • Four pairs of eyes.
• Number of Legs: Eight walking legs.

Insecta (Ants, Beetles, Bees, Grasshoppers)

• Body Organization:
  1. Head
  2. Thorax
  3. Abdomen
• Specialized Structures:
  • One pair of antennae.
  • Six walking legs.
  • Most have one or two pairs of wings.
  • Specialized mouthparts.
  • Oxygen enters in holes called spiracles & circulates through tracheae.
  • Liquid waste extracted by Malpighian tubes.