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AP Biology. Lecture #49 Non-Vertebrate Animals. Characteristics of Animals. Animals are: Multicellular Heterotrophs Eukaryotic Have tissues and differentiated cells Eat Reproduce and Develop 1.3 millions species have been identified, estimates of 10 to 200 million exist. - PowerPoint PPT Presentation
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AP Biology
Lecture #49Non-Vertebrate Animals
Characteristics of Animals
• Animals are:• Multicellular• Heterotrophs• Eukaryotic• Have tissues and differentiated cells• Eat• Reproduce and Develop• 1.3 millions species have been identified,
estimates of 10 to 200 million exist
Early Embryonic Development• Sperm and egg meet
through fertilization to form a zygote
• The zygote undergoes mitosis, called cleavage
• A blastula, or multi-celled hollow ball forms
• These cells form tissue layers that make up a gastrula
Eras of Animal Life
• Neoproterozoic Era (1 B 542 mya): First fossilized animals are from this time period.
• Paleozoic Era (542 251 mya): the Cambrian explosion occurs, huge diversity of animal species, including vertebrates, evolve
• Mesozoic Era (251 65.5 mya): animal life spreads across the planet
• Cenozoic Era (65.5 mya present): dinosaurs, birds, and mammals all evolve
Body Plans
• Animals can have radial symmetry, in which the parts of an animal radiate out from the center (starfish)
• Or they can have bilateral symmetry, with equal left and right sides (lobsters, humans)
• Animals with a distinct forward facing head at the top of the body have gone through cephalization.
Tissue Layers• The tissue layers of an animal
embryo are called germ layers, and form organs.
• The ectoderm is the outermost layer and forms the skin and nervous system.
• The endoderm is the inner layer of the embryo and turns into the digestive system.
• Some animals have a third layer, called the mesoderm, which forms the other body organs.
Body Cavities
• Some animals have body cavities, a fluid-filled space that separates the digestive tract from the outer body wall, this is called a coelom.
• Pseudocoelomates have a body cavity that is formed from a different type of tissue.
• Acoelomates do not have body cavities.
Protostomes and Deuterostomes• Protostomes, like
worms and bugs, develop a mouth first during fetal development.
• Deuterostomes, like people and starfish, develop an anus before they develop mouths.
Invertebrates
• Invertebrates are animals without a backbone.• The main phyla we will talk about are:
– Porifera– Cnidaria– Platyhelminthes– Nemotodes– Mollusks– Annelids– Arthropods– Echinodermata– Some chordates
Invertebrates
Parazoa
• Invertebrates: animals without backbones
• Closest lineage to protists
• Loose federation of cells (unspecialized); no tissues
• Phylum.: (only one) Porifera (sponges)
The Sponges – Phylum Porifera
• Phylum Porifera are the sponges.• They may have radial symmetry, or no
symmetry.• They are non-motile filter feeders.• Individual cells are specialized, but they have
no true organs.
Phylum Porifera
General InformationSize range – 1 cm to2 meters in diameter
Giant Barrel sponges
Eumetazoa: Animals with true body tissueThe Radiata, I
• Diploblastic• Radial symmetry• Phylum: Cnidaria (hydra, jellies, sea
anemones, corals)– tissues, but no organs– two cell layers– predators
• tentacles surround gut opening
• extracellular digestion– release enzymes
into gut cavity– absorption by cells
lining gut
hydra
stinging cellwith nematocyst
trigger
dischargednematocyst
undischargednematocyst
tentacles
mouth
sensorycell
stingingcell
Stinging cells of Cnidarians
The Radiata, II
• Phylum: Ctenophora (comb jellies)
• 8 rows of comblike plates of fused cilia (largest animals that use cilia for locomotion)
• Tentacles with colloblasts (adhesive structures that capture prey)
Eumetazoa: The Acoelomates• Phy: Platyhelminthes
(flatworms, flukes, tapeworms)
• Bilateral; no body cavity• Predators, scavengers,
parasites• Some cephalization~
development of brain concentration of sense organs in head
ectoderm
mesoderm
endodermacoelomate
Eumetazoa: Pseudocoelomates, I
• Body cavity partially derived from mesodermally derived tissue
• Phylum: Rotifera• 1st with a complete
digestive tract• Hydrostatic skeleton• Parthenogenesis: type of
reproduction in which females produce offspring from unfertilized eggs
Eumetazoa: Pseudocoelomates, II
• Phylum: Nematoda (roundworms)
• Very widespread group of animals (900,000 sp. ?)
• Cuticle (tough exoskeleton)• Decomposition and nutrient
cycling• Complete digestive track; no
circulatory systemmany are parasitic
• hookworm• Trichinella spiralis
C. elegans
The Coelomates: Protostomes, I
• Phylogenetics debated….• Phy: Nemertea (proboscis and
ribbon worms)• Complete digestion and closed
circulatory system (blood)• Phy: the lophophorates (sea
mats, tube worms, lamp shells)• Lophophore: Circular shaped
body fold with ciliated tentacles around the mouth
The Coelomates: Protostomes, II• Phylum: Mollusca (snails,
slugs, squid, octopus, clams, oysters, chiton)
• Soft body most protected by a hard shell of calcium carbonate
• Foot (movement), visceral mass (internal organs); mantle (secretes shell); radula (rasp-like scraping organ)true coelem• increases complexity &
specialization of internal organs
• There are 3 types of mollusks:• Gastropods: sea slugs, snails and slugs• Bivalves: clams, oysters, mussels, and scallops
(2 hinged shells)• Cephalopods: built for speed and motility,
include squid and octopi; have sophisticated sense organs.
Phylum Mollusca
Class Cephalopoda squids, octopus, cuttlefish, nautilus
The Coelomates: Protostomes, III• Phylum: Annelida
(earthworms, leeches, marine worms)
• True body segmentation (specialization of body regions)
• Closed circulatory system• Metanephridia: excretory
tubes• “Brainlike” cerebral
ganglia• Hermaphrodites, but
cross- fertilize
leechfan worm
The Coelomates: Protostomes, IV• Phy: Arthropoda trilobites
(extinct); crustaceans (crabs, lobsters, shrimps); spiders, scorpions, ticks (arachnids); insects (entomology)
• 2 out of every 3 organisms (most successful of all phyla)
• Segmentation, hard exoskeleton (cuticle)~ molting, jointed appendages; open circulatory system (hemolymph); extensive cephalization
Arthropod groups
insects6 legs, 3 body parts
crustaceansgills, 2 pairs antennaecrab, lobster, barnacles, shrmp
arachnids8 legs, 2 body partsspiders, ticks, scorpions
The Coelomates: Deuterostomes, I
• Phylum: Echinodermata (sea stars, sea urchins, sand dollars, sea lilies, sea cucumbers, sea daisies)
• Spiny skin; sessile or slow moving
• Often pentaradial• Water vascular system• They are radially symmetrical
as adults, and bilateral as larvae.
Water Vascular System
• Madreporite• stone canal• ring canal• radial canal• lateral canals• Ampulae• tube feet