Transcript Animalia Arthropoda - HRSBSTAFF Home Page

Kingdom: Anamalia
Phylum:Arthropoda
ABDI ISSAK
FINNBAR MARTIN
VALON DAKA
Types of Arthropod
There are three main groups of Arthropods:
 Arachnids: Insects with 8 legs
 Crustacean : Free living aquatic animals
 Myriapoda: Creatures with many legs up to 375
pairs. (750 legs)
Anatomy
 Arthropods have jointed legs, head and segment body, otherwise
known as the thorax. Their bodies are covered with a hard shell or a
hard outer skin called exoskeleton. With crustaceans the exoskeleton is
known as the carapace and hides the body parts.
Physiology
 Arthropod physiology for breathing has thankfully restricted the
maximum size they can achieve. As has their reliance on their
exoskeleton which cannot support the weight of an animal beyond a
fairly small size. Although some arthropods are large. The arthropods
bloodstream is open. The coelom is much small and most of the spaces
inside it’s body are body cavities.
Locomotion
 The walk of an arthropod walk is made up of a propulsive backstroke,
and the recovery forward stoke. While it uses it’s remoter, the foot is in
contact with the substrate, and during the promoter it is raised. The
promotor/remotor sequence is known as a step cycle.
 Arthropods move the same leg on each side of the body at the same
time. This walking technique is less stable than out-of-phase walking,
and is generally practiced by arthropods walking underwater
Obtaining Food
Arachnids:
 They engage in many ways to obtain food. Some spiders
trap their victims in silken webs and kill them with a
poisonous bite. Others ambush their prey and overpower
them with their strong legs before biting them.
 Scorpions use their claws to capture and kill prey, or else
they kill them with a venomous sting. Sun spiders use
lightning speed and their massive mouthparts to outrun
and tear apart prey
Crustacean:
 Some crustaceans like shrimp and Krill use
filter feeding to obtain their foods. They feed by
straining suspended matter and food particles
from the water.
 Other crustaceans such as crabs and lobsters
are scavengers and are predators. They use
there claws to attack prey, crush them and then
eat them.
Myriapoda:
 The centipede (a type of Myriapoda)
has a gland in its head that fills the
fangs with poison. The centipede
uses this poison to kill its prey.
 Centipedes have poor eyesight and
detect prey by their movement and
vibrations.
 Mostly centipedes will not eat any
dead matter but some other
Myriapods (like millipedes) will.
Diet
Arachnids
 Arachnids attack and kill small animals, especially
insects and their relatives, and then feed on their
body fluids. Since they cannot chew most arachnids
must first digest their food outside their bodies.
 They pierce tissues with their mouthparts and inject
them with digestive chemicals, turning them into
fluids. The fluids are then sucked through the mouth
and into the body.
Crustaceans:
 Crabs which are a known type of Crustacean usually
feed on algae but take in any food including other
Crustaceans. For the most part mixed diet of plant
and animal matter result in fastest growth of the
Crustacean species.
Myriapoda:
 Myriapods eat different types of food. Some are
carnivores, which means they eat other mini-beasts.
Others are herbivores, which means they eat plants.
 Centipedes are predators so they feed on other minibeasts. They hunt at night and are poisonous to other
animals.
 Millipedes eat dead plants and animals. Millipedes
are useful because they help clear away rotting
vegetation.
Digestion
Arachnids:
 The digestive system is a tube that begins with the
mouth, situated below the chelicerae, and leads into
the pharynx, then into the esophagus, and from there
into the sucking stomach, which has heavy muscles
and serves to pump the partially digested food into
the mid-gut, where special enzymes digest the food.
Crustaceans:
 Digestion occurs in the foregut which shows the
greatest range of structure; in some crustacean
species it is a simple tube, but in crustacean's with 5
pairs of feet it reaches great complication in forming
a structure called the gastric mills . This consists of a
series of calcified plates, or small bone, that are
moved against each other by powerful muscles,
making an efficient grinding apparatus. The junction
between the mill and the midgut is guarded by a
filter.
Myriapoda:
 The digestive system is a gut that runs from the
mouth to the anus.
 The gut is lined with a protective outer covering
called a chitin, that is shed every so often.
Excretion
 Undigested food becomes solid waste
 It leaves the anus of the animal.
 Terrestrial arthropods remove nitrogen-containing wastes by:
using a set of Malpighian tubules
 Found in the body sinuses
remove waste from blood, concentrate them, and then add
undigested food allowing it to leave through anus
may have small excretory glands at bases of legs.
 Aquatic arthropods remove nitrogen-containing wastes by...
through a pair of green glands found by base of antennae
eliminated through a pair of opening on the head.
Circulation
 Arthropods' primary internal cavity is a hemocoel, which
accommodates their internal organs and through which
their bloodcirculates; they have open circulatory systems.
Like their exteriors, the internal organs of arthropods are
generally built of repeated segments. Their nervous
system is "ladder-like", with paired ventral nerve
cords running through all segments and forming
paired ganglia in each segment. Their heads are formed by
fusion of varying numbers of segments, and their brains are
formed by fusion of the ganglia of these segments and
encircle the esophagus
Respiration
 Respiration in the arthropods occurs through
microscopic holes in the exoskeleton and body
wall. Branching networks called tracheae extend
from these holes to all parts of an arthropod's
body.
Life Cycle
 Arthropods begin as eggs and can follow several
different life cycles, depending on the group. Some
insects hatch as miniature adults, while others hatch
as nymphs and develop by stages into adults. Still
others hatch as larvae and enter a resting stage as
pupae, during which they may be enclosed in a
cocoon and go through internal changes before
emerging as adults. During their various
developmental stages, known as metamorphosis,
arthropods may shed their outer covering several
times.
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Bibliography
 http://serge.mallet.pagesperso-orange.fr/myriapoE.html
 http://www.learninghuddle.com/wildlife/miniBeasts/index.php/ho
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 http://www.biology-online.org/10/6_arthropods.htm
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 http://animals.jrank.org/pages/2264/Spiders-Scorpions-Mites
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