Download Which group is the sponges?

Kingdom Animalia
•Multicellular
•Eukaryotic
•Heterotrophs
•Cells lack cell wall
Trends in animal evolution:
•Asymmetrical, radial symmetry, bilateral symmetry
•Cephalization
•Sessile, motile
•Specialized cells, tissue, organs, systems
•Body cavity formation (coelem)
•Embryology and germ layer development
Animal Web Home
Diversity of Animals
Phylum Porifera:
The Sponges
Structure and Filter Feeding Mechnism
Diversity information, pictures, classification
Characteristics of Poriferans:
•“pore bearers”
•Sessile (attached to a fixed point)
•Asymmetrical (no front or back, left or right)
•No tissue or organs, only specialized cells
•Filter feeders
•Water flows in through pores and out through osculum
•Choanocytes use flagella to move water through the sponge
•Skeleton of spicules (silica or calcium carbonate) or spongin
(flexible protein fibers)
•Reproduce by budding or sexually
•Provide habitats for smaller animals and form mutualistic
relationships with photosynthetic organisms
Phylum Cnidaria:
The Stinging Cell Animals
Diagram of a Cnidocyte
Diversity information, pictures, classification
Characteristics of Cnidarians:
•Include jellyfish, coral, hydra, and sea anemones
•Motile or sessile
•Radial symmetry
•Cnidocytes with nematocysts
•Specialized tissue…primitive “nervous system” called a nerve net.
•Polyp and/or medusa body forms.
Phylum Platyhelminthes:
The Flatworms
Diversity information, pictures, classification
Characteristics of Flatworms:
•Include free-living species, tapeworms, flukes
•Have tissue and organ systems
•Bilateral symmetry
•Cephalization
•Three embryonic germ layers
•Acoelomates (no fluid filled body cavity)
•One-opening digestive system in planaria (Pharynx leads to mouth)
•Diffusion for tapeworms (no digestive system)
•Ganglia; gathering of nerve cells near anterior end (beginnings of a brain)
•Nerve cords
•Eyespots and other receptors
•Circulation not necessary because they’re flat (diffusion is adequate)
•Flame cells for excretion
•Hermaphrodites (both male and female reproductive organs)
•Complex life cycles for parasites
Phylum Nematoda:
The Roundworms
Diversity information, pictures, classification
Characteristics of Roundworms:
•Unsegmented, tapered ends
•Free-living in soil and water
•Parasites of many kinds of plants and animals
•Trichinella, filarial worms, Ascaris, hookworms
•Digestive system with two openings (mouth and anus)
•Pseudocoelem (body cavity between endoderm and mesoderm)
Phylum Annelida:
The Segmented Worms
Characteristics of Annelids:
•Earthworms, leeches, sandworms,
bloodworms
•Segmented bodies
•True coelem lined with mesoderm
•More advanced body systems
•Digestion; pharynx, crop, gizzard,
intestine
•Circulation; closed circulatory system
(blood vessels)
•Aortic arches act as tiny pumping
hearts
•Excretion; Nephridia- organs that filter
fluid in the coelem
•Nervous; brain, ganglia, nerve cords
•Reproduction; hermaphrodites…use
clitellum to exchange sperm
Diversity information, pictures, classification
Ventral view
Digestive & Circulatory
Phylum Mollusca:
The Soft-bodied Animals
Diversity information, pictures, classification
Characteristics of mollusks:
•Snails, slugs, clams, oysters, scallops, octopi, squid, cuttlefish,
nautilus
•Soft-bodied animals that usually have an internal or external
shell
•Closely related to annelids…both have a free-swimming larval
stage called a trochophore
•Have a true coelem lined with mesoderm
•Body plan contains four parts: foot, mantle, shell, and visceral
mass
•Open or closed circulatory system
•Carnivores, herbivores, filter feeders, detritivores, parasites
•Advanced and complex sense organs, intelligence in the
cephalopods
Phylum Arthropoda
The Jointed-Leg Animals
Diversity information, pictures, classification
Characteristics of Arthropods:
•Jointed appendages
•Exoskeleton of chitin
•Segmented bodies (like annelids)
•Specialized appendages for feeding, movement, etc.
•By far the most successful phylum of animals
•85% of all living animal species are arthropods
Phylum includes:
Crustaceans (crab, shrimp, lobster, crayfish, barnacles)
Chelicerates (spiders, mites, ticks, scorpions, horseshoe crabs)
Uniramians (insects, millipedes, centipedes)
Factors leading to Insect success:
1. Small size
2. Coevolution with flowering plants
3. Metamorphosis (complete or incomplete)
Two specialized life stages
Complete; egg, larva, pupa, adult
Incomplete; egg, nymph, adult
4. Tough exoskeleton (chitin with waxy covering in some)
Molting to grow
5. Flight
6. Rapid multiplication/short life cycle…evolve quickly
7. Sense organs, specialized mouthparts and appendages
Insect Communication
Waggle Dance
Phylum Echinodermata:
The Spiny Skin Animals
Diversity information, pictures, classification
Characteristics of Echinoderms:
•Include sea stars, brittle stars, sea urchins, sand dollars, sea
cucumbers, sea lilies, feather stars
•Spiny skin of calcium carbonate
•Internal skeleton
•Water vascular system
•Tube feet (suction cups on legs)
•Radial symmetry
Then why didn’t we study these with Cnidarians???
Echinoderm larvae are bilaterally symmetrical indicating
that symmetry evolved independently in this group.
In the embryonic development, echinoderms are more
similar to chordates…they are both deuterostomes.
So although they exhibit radial symmetry, we do not
consider echinoderms to be primitive animals.
Invertebrate quick check…
Which group includes snails, clams, and squid?
Which group is the sponges?
Which are the flatworms?
…segmented worms?
…roundworms?
Which group has jointed appendages & an
exoskeleton?
Which two groups are radially symmetrical?
Which group has no symmetry?