Echinoderms have a spiny skin and bone plates just below it that form an endoskeleton. Fish are cold-blooded vertebrates that live in water and breathe through gills. They have scales, fins, and well-developed circulatory, digestive and nervous systems. Invertebrates lack a backbone and have less developed nutrition and sensory systems compared to vertebrates. They may have exoskeletons, endoskeletons, or no skeleton.

1. Echinoderms
The starfish is one of the members of the phylum Echinodermata , a group of marine
invertebrates that has a spiny skin. The animals belonging to this group are called
echinoderms .
The spines projecting from a bone plates that are just below the layer of soft leather .
These plates form an endoskeleton . An endoskeleton is a skeleton which is within the
body of an animal .
• The Myriapoda
are terrestrial invertebrates group arthropods characterized because they have the
elongated body and divided into two parts ( head and trunk) . The head is provided
with a pair of antennas and the body is formed by a very large number of rings or
segments provided with one or two pairs of legs each. Boca masticatory and
development without metamorphosis. His body is covered with chitin.
• The Fish

2. The characteristics of the fish
Fish are vertebrates that live in water and breathe through gills. They are ectothermic ;
ie , cold-blooded animals . A ectotermo is an animal that gets the heat of his body ,
mainly the environment. The fish have the backbone of cartilage or bone . Most of the
fish are adapted to living in fresh or salt water. Most have fins.
Most fish have scales that cover and protect the body. Circulatory, digestive and
nervous systems of fish are very well developed . There are three kinds of fish : The
Agnatha , Chondrichthyes and Osteichthyes the . The earliest of the three classes is the
jawless fish (the Agnatha ) . Sharks and mantas ( stripes ) are the class Chondrichthyes .
The largest class is the Osterichthyes . The fish of this class have a skeleton made
almost entirely of bone.
• roundworms
It is a pest that causes considerable damage to garden crops .
The types of roundworms are various: some attack inside the roots ( Heterodera
rostochiensis , Pratylenchus and Melogyne ) , others live in the outer part of roots (
Tylenchides and Dorilaimides ) and others attack the aerial part of the stem.
Roundworms are divided into roundworms Ascardiasis , Pinworms , Trichurdiasis ,
Uncinariasis .
• The flatworms

3. They are worms with dorsoventrally flattened body and digestive tract devoid of year.
Nor have circulatory system and most are hermaphrodites. Almost always parasites.
There are locomotor appendages and some have cilia.
Mostly lack digestive, circulatory, respiratory , and sensory organs. They usually have
suction pads .
• Birds
Birds belong to the phylum Chordata , subphylum Vertebrata and the class Aves. They
are endothermic vertebrates with feathers. Most birds have similar body structures .
Order to distinguish one from another , taxonomists have for variations in bone
structure , in losmúsculos and internal organs .
• Invertebrates

4. Invertebrates are the most primitive multicellular animals group, which means less
development of nutrition systems ( digestive, circulatory ... ) and relational ( nervous
system, sense organs .
Unlike vertebrate , this group is characterized by the absence of backbone . However ,
may , however , have other skeletal structures serve qque protection and support. The
shells of some mollusks exoskeleton exemplify or extern skeleton surrounding or
encircling the body of the animal.
Other invertebrates , such as sponges , presenting skeletal parts inside , internal
skeleton endoskeleton one speaks of or .
• No Vertebrates Mammals , Fish
Fish are vertebrates to aquatic life . Logically their way of swimming motions so that
the fusiform shape ( bone ) was provided presented . Furthermore developed
appendages , the fins adapted to displacement in the water. Generally have two pairs
of alestas p ( ventral pectoral ) and three major fins (dorsal, anal and caudal) .
Fish live in both the sea and in fresh water ( rivers and lakes) , from shallow waters to
depths let them know where the darkness is total. Are known to exist in these regions
producing organs of fish with light ( luminescent ) .
Another easy features observed is the absence of eye lids , which therefore remain
always open , and the presence of several rows of teeth in the mouth . They lack
external ears , but are able to perceive sounds , YA having inner ears .
• The Arachnids
Spiders , scorpions . Ticks and mites are arthropods of the class Arachnida . They are a
very large class in the subphylum Chelicerata , each spider has four pairs of walking
legs , chelicerae , pedipalps , simple eyes and no antennae . The simple eyes called
ocelli . The body of an arachnid has two parts ; cephalothorax and abdomen.
• Amphibians

5. The characteristics and classification
Amphibians are vertebrates that have gills as larvae and are usually lungs as adults.
Amphibians , class Amphibia were the first vertebrates to adapt to life on land. After
the eggs hatch , the majority of young amphibians are aquatic and breathe through
gills . As adults , amphibians live on land, at least part time and breathe through lungs.
Of the three groups of amphibians, the best known and abundant is the frogs and
toads . The order Anura include frogs and toads, no tail and have two pairs of legs. The
hind legs are much larger than the front .