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KEY CONCEPT Animals are diverse but share common characteristics. . Animals are the most physically diverse kingdom of organisms. Animals range in size from 25-meter-long blue whales to microscopic rotifers. Animals are found nearly everywhere on Earth. - PowerPoint PPT Presentation
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23.1 Animal Characteristics
KEY CONCEPT Animals are diverse but share common characteristics.
23.1 Animal Characteristics
Animals are the most physically diverse kingdom of organisms.• Animals range in size from 25-meter-long blue whales
to microscopic rotifers. • Animals are found nearly everywhere on Earth.
23.1 Animal Characteristics
All animals share a set of characteristics. • All animals share a unique set of derived
characters.• Animal cells are
supported by collagen. – three-stranded
protein– found in bone,
skin, ligaments,fingernails,and hair
23.1 Animal Characteristics
– diploid parents produce diploid offspring• Animals are diploid and usually reproduce sexually.
Diploid cells have two copies of each chromosome: one copy from the mother and one from the father
– do not have free-living haploid life stages
23.1 Animal Characteristics
– Homeotic genes control early development.– Hox genes determine the position of cells differentiation.– A Hox gene mutation leads to the development of a body
structure in the wrong position.
• Most animals have Hox genes.
23.1 Animal Characteristics
• Differences in body plans result from differences in the expression of Hox genes.– Hox genes tell embryonic cells which body part to
become. – Mutations in Hox genes led to the vast diversity of
animal species.
head tail
headtail
fruit fly genes
human HOX-B genes
23.1 Animal Characteristics
Each animal phylum has a unique body plan. • Vertebrates have an internal segmented backbone.• Invertebrates do not have a backbone.• Invertebrates encompass most animal groups.
23.1 Animal Characteristics
Animals are grouped using a variety of criteria. • Three criteria are used to
categorize animals. – body plan symmetry– tissue layers – developmental patterns
gastrovascular cavity
mouthmesoglea
oral arms
tentacles
blood vessels
brain
heartsmuscle
segment nerve cord
mouth
digestive track
23.1 Animal Characteristics
• There are two types of body plan symmetry.– bilateral symmetry: body divides equally along one plane
Animals with bilateral symmetry can be divided equally along only one plane, which splits an animalinto mirror-image sides.
23.1 Animal Characteristics
– radial symmetry: body arranged in circle around a central axis
• There are two types of body plan symmetry.– bilateral symmetry: body divides equally along one plane
Animals with radial symmetry have body parts arranged in a circle around a central axis.
23.1 Animal Characteristics
Types of Symmetry
23.1 Animal Characteristics
Symmetry Practice
23.1 Animal Characteristics
Germ Layer Tissue• Germ layer tissues are aligned in specific positions in an embryo
and eventually give rise to all of an animal’s tissues and organs.– Endoderm-inner most layer, develops into the linings of the
digestive tract and much of the respiratory system– Mesoderm-middle layer, gives rise to muscles and most internal
organs– Ectoderm-outermost layer, gives rise to nervous system and skin
• Simpler organisms with radial symmetry only have endoderm and ectoderm.
23.1 Animal Characteristics
23.1 Animal Characteristics
Body Cavities• Acoelomates- have no coelom, or body cavity• Pseudocoelomates-have a false or partially lined body
cavity with only 1 side being covered with mesoderm• Coelomates-have a true body cavity, both sides of the
body cavity are lined with mesoderm
23.1 Animal Characteristics
23.1 Animal Characteristics
Gastrulation• Gastrulation is an interior
movement of cells that results in a reorganization of the embryo from a simple spherical ball of cells, the blastula, into a multi-layered organism. Two types:– Protostomes form mouth-first,
and anus second.– Deuterostomes first form the
anus and then the mouth.
23.1 Animal Characteristics
A comparison of structure and genetics reveals the evolutionary history of animals.• Protostomes and deuterostomes are the two major
radiations on the animal phylogenetic tree. Porifera Cnidaria Platyhelminthes Annelida
Mollusca Nematoda ArthropodaEchinodermata
Chordata
RADIAL
NO TISSUES
PROTOSTOMESDUETEROSTOMES
jelly
fish,
cor
al, a
nem
ones
spon
ges
flatw
orm
s
Seg
men
ted
wor
ms
clam
s, s
nails
,oc
topu
ses
roun
dwor
ms
crus
tace
ans,
inse
cts,
spi
ders
sea
star
s,
sea
urch
ins
lanc
elet
s,ve
rtebr
ates
23.1 Animal Characteristics
• The current organization of the animal kingdom shows some unexpected relationships.
• Technological advancementshelp to clarify evolutionaryrelationships.