Download Arthropods (Phylum Arthropoda)

Characteristics
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Bilateral Symmetry
Cephalization
Coelomates (true body cavity)
segmented bodies covered by a hard exoskeleton
jointed appendages
There are five common classes of arthropods:
Crustacea, which includes crayfish lobsters and
shrimp; Arachnida, which includes spiders, ticks and
scorpions; Insecta, which comprises insects; and
Chilopoda for centipedes and Diplopoda for
millipedes.
More Characteristics
 Exoskeleton- hard outer shell/skeleton that helps to
protect, support, give shape, hold in water. Composed
of Chitin
 Appendages-arms, legs, antennae…parts that extend
from the body.
 Can be herbivores, carnivores, omnivores, detrivores,
filter feeders, or parasites.
Respiration
 How they obtain oxygen from the air or water.
 Terrestrial Arthropods(land dwelling)- have a network
of tracheal tubes that extend thru their body.
 Some have more specialized ‘book lungs’ which are
layers of respiratory tissue like pages in a book.
 Aquatic Arthropods (water dwelling)-use gills
Circulation
 How they move oxygen and remove carbon dioxide
thru their body
 Arthropods have an Open Circulatory System (blood
leaves the blood vessels at some point).
 Blood pumps from the HeartArteries*leaves the
blood vessels*enters sinuses or cavities leading to
organsblood pools and collects pumps back to the
heart.
Excretion
 How waste is removed from the blood (nitrogenous
waste)
 Arthropods have specialized structures called
Malpighian tubules that extract waste from the blood
and add them to digestive wastes.
 The waste is then removed through the gut (digestive
tract) of the arthropod.
Response
 Most arthropods have a well-developed nervous
system.
 All arthropods have brains.
 They also have a series of ganglia (nerve bundles)
which help to coordinate movement of the many body
segments.
 Many arthropods have very specialized sense organs.
Movement
 Arthropods move using well developed groups of
muscles that are coordinated and controlled by the
nervous system.
Reproduction
 Sexual Reproduction
 Terrestrial arthropods all have internal fertilization.
 Either the male reproductive organ places the sperm inside
the female and fertilization occurs, or the male deposits
sperm packets that are picked up by the females for
internal fertilization.
 Aquatic arthropods may have internal or external
fertilization.
 External fertilization occurs when females release their egg
into the external environment and males release sperm
around the eggs
Phylum Echinodermata
Characteristics
 No anterior and posterior end
 No cephalization (no head area)
 2 sided bodies
 Spiny skin, internal skeleton
 Water vascular system, excretory and nervous system
 Suction cup like tube feet
 Radial symmetry
 Usually 5 parts
Water Vascular System
 Circulation, respiration, movement
 Oxygen food and wastes are circulated
and carried throughout the organisms
Reproduction
 Reproduction Echinoderms reproduce by external
fertilization.
 Sperm are produced in testes, and eggs are produced
in ovaries.
 Sperm and eggs are deposited into open water where
fertilization occurs
 The larvae, which have bilateral symmetry, swim
around for some time and then swim to the ocean
bottom, where they develop into adults that have
radial symmetry.
Examples
 There are roughly 7000 species of
echinoderms—all of which live in the
world’s oceans
 Classes of echinoderms include sea urchins
and sand dollars; brittle stars; sea
cucumbers; sea stars; sea lilies and feather
stars.