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Kingdom Animalia: Invertebrates . Chapter 11. Kingdom Animalia . All members of the animal kingdom have cells that lack a cell wall and only have a cell membrane All heterotrophic Scientists who study zoology divide this complex kingdom into two groups: Invertebrates Vertebrates.
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Kingdom Animalia: Invertebrates Chapter 11
Kingdom Animalia • All members of the animal kingdom have cells that lack a cell wall and only have a cell membrane • All heterotrophic • Scientists who study zoology divide this complex kingdom into two groups: • Invertebrates • Vertebrates
Phyla of the Animal Kingdom • Porifera • Cnidaria • Platyhelminthes • Nematoda • Rotifera • Annelida • Mollusca • Arthropoda • Echinoderma • Chordata
Porifera - Sponges • Simplest / most primitive of the animals • Specialized cells, but no tissues or organs • No nervous system or brain • Most sponges are hermaphrodites • Only produce one types of gamete at a time, so they still produce sexually • Fertilized egg turns into a free swimming larva, which attaches to the bottom and undergoes metamorphosis
Cnidaria • Name comes from the Greek word “knidae”, meaning nettle or stinging hairs • Includes hydra, jellyfish, sea anemones and coral • All are radially or bilaterally symmetrical, have tentacles and posses true tissues • Body structure comes in 2 forms: • Polyp - sessile • Medusa - mobile
Cnidaria Cont’d. • Capture small prey using specialized stinging cells that contain nematocysts • They inject a toxin which can paralyze the prey • Food is digested in a singular gastrovacular cavity, and enters and leaves through the same opening • Mostly produce sexually • Hydras and coral usually produce asexually through budding.
Platyhelminthes • Commonly known as the flatworms • Most primitive animal to show bilateral symmetry and cephalization • They have two forms: • Parasitic (ex: tapeworm) • Very simple reduced digestive system • Highly developed reproductive system • Free Living (ex: Planaria) • Lives in moist or aquatic environments • Hermaphroditic, a reproductive system is present for the breeding season and then degenerates for the remainder of the time
Nematoda • Commonly known as round worms • Most are small, free-living and harmless, however some are parasitic and can do serious damage • Simplest organisms to have a complete digestive tract, including a mouth and an anus • Respiration is still through simple diffusion • Examples: • Hookworms • Heartworms
Rotifera • Commonly referred to as wheel animals, are microscopic or near microscopic animals. • Common in freshwater environments • Rotifers eat particulate organic detritus, dead bacteria, algae, and protozoans • Males can be absent, and females reproduce by parthenogenesis OR females can produce males that lack a digestive system but have a full reproductive system
Annelida • Known as the segmented worms • Segmented body is beneficial for locomotion • Posses a coelom • Includes: Earthworms, red worms, leeches and polychaetes • No central heart but has thickened muscular blood vessels in the anterior region which act as a pump • A large dorsal ganglion acts as a brain
Mollusca • Second largest phyla in the animal kingdom • There is a huge amount of diversity, and the 3 main classes of this phyla are: • Gastropods (snails and slugs) • Bivalves (clams and oysters) • Cephalopods (squid and octopus) • All mollusks are protostomes • Meaning to mouth develops first during gestation
Arthropoda • The largest of the animal kingdom phyla • Contains about 90% of all animal species • Inhabit very diverse environments, and have been found in almost all environments • The phyla includes: • Insects • Scorpions • Spiders • Mites and Ticks • Crabs and Lobsters • Centipedes and Millipedes
Arthropods Cont’d • A key characteristic that distinguishes arthropods is their exoskeleton • A hard external skeleton made of chitin • The exoskeleton does not grow with the arthropod, so the organism moults, shedding it’s old cuticle • Has a primitive nervous system • Eyes may be simple or complex with few or many photoreceptors
Arthropods Cont’d. • Have an open circulatory system • All arthropods have a digestive system with 3 parts: • Foregut – mouth, esophagus, crop or gizzard • Midgut – stomach • Hindgut – intestines to the anus • All reproduce sexually • Many groups have a larval stage
Echinodermata • Many different types of locomotion within the phyla: • Sessile (sea lilies) • Burrowing (sand dollar) • Crawling (starfish) • All are deuterostomes • Meaning the anus forms first and the mouth forms second • Water vascular system • Fluid filled tubes throughout the body used for locomotion and feeding
Chordata • Make up only about 5% of all known animal species • One of the most recent groups of animals • Huge amount of diversity in this phyla • All reproduce sexually