Animalia Seven Phylum

Phylum Porifera: "From the Latin porus for pore and Ferre to bear, hence an animal with with pores," (The Phylum Porifera). This phylum has different types of sponges. Sponges, "are considered the oldest animal group. They are multicellular but don’t have tissues or organs," (Phylum Porifera). They have channels, which give their shape, and each "channels lead to inner chambers lined with specialized feeding cells called choanocytes or collar cells," (Porifera). Its characteristics include (Phylum Porifera: General Characters and More);

They are the most primitive metazoans.
Sponges are multicellular animals lacking specialized tissues and organs.
Body grows to various shapes. Most of them are asymmetrical and some are radially symmetrical.
They are diploblastic animals (Having two germ layers ectoderm(pinacoderm) and endoderm(chanoderm).
They are simple animals having cellular level of organization. Cells are not organised to tissues or organs.

They lack a metazoan type of digestive system. They rely entirely on intracellular digestion.
Mouth, digestive cavity and anus are absent.
Nervous system and sense organs are also absent.
Reproduction is both by sexual or asexual means.

Asexual reproduction takes place by budding or by specialized cell called gemmules. Gemmules develop into new sponges during favourable conditions.
Life cycle includes ciliated free swimming larvae called amphiblastula or parenchymula.
Sponges show greater power of regeration

Meet Ircinia felix;

(Stinker Sponge (Ircinia Felix))

Phylum Cnidaria: "Cnidarians are radially or biradially symmetric, a general type of symmetry believed primitive for eumetazoans," (Cnidaria (corals, Sea Anemones, Jellyfish, and Relatives)). They include such diverse form of organisms as jellyfish, hydra, sea anemones, and corals. They have achieved the tissue level of organization (i.e tissues), but lack organs (Cnidaria). They have two basic body forms; medusa and polyp. Medusa body are free-swimming bodies, while polyp are tubular bodies (The Wonders of the Sea). Its characteristics includes (The Phylum Cnidaria);

Radially Symmetrical.
Body multicellular, few tissues, some organelles.
Body contains an internal cavity and a mouth.
Two different forms exist, medusa and polyp
Reproduction is asexual or sexual.
Has a simple net like nervous system.
Has a distinct larval stage which is planktonic.
Lives in aquatic environments, mostly marine.
Mostly carnivorous otherwise filter feeders.
May have a minimal skeleton of chiton or calcium carbonate.

Meet Marivagia stellata;

Phylum Platyhelminthes: It is a "phylum containing about 20,000 species of soft-bodied, bilaterally symmetrical, invertebrate animals, commonly called flatworms," (Platyhelminthes). While some forms are free living many others are parasitic (Platyhelminthes (flatworms)). They have no body cavity other than the gut and lack an anus; the same pharyngeal opening both takes in food and expels waste, "The lack of a cavity also constrains flatworms to be flat; they must respire bydiffusion (Introduction to the Platyhelminthes). Its characteristics includes (The Phylum Platyhelminthes);

Bilaterally symmetrical.
Body having 3 layers of tissues with organs and organelles.
Body contains no internal cavity.
Possesses a blind gut (i.e. it has a mouth but no anus)
Has Protonephridial excretory organs instead of an anus.
Has normally a nervous system of longitudinal fibres rather than a net.
Generally dorsoventrally flattened.
Reproduction mostly sexual as hermaphrodites.
Mostly they feed on animals and other smaller life forms.
Some species occur in all major habitats, including many as parasites of other animals.

Meet Xenoturbella hollandorum;

Phylum Annelida: Segmented worms that includes earthworms, polychaete worms, and leeches (Introduction to the Annelida). "All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity," (Annelida (segmented Worms)). Each segment has different body systems as circulatory, nervous, and excretory tracts and it makes possible the development of greater complexity in general body organization (Annelida (segmented Worms)). Its characteristics includes (The Phylum Annelida);

Bilaterally symmetrical and vermiform.
Body has more than two cell layers, tissues and organs.
Body cavity is a true coelom, often divided by internal septa.
Body possesses a through gut with mouth and anus.
Body possesses 3 separate sections, a prosomium, a trunk and a pygidium.
Has a nervous system with an anterior nerve ring, ganglia and a ventral nerve chord.
Has a true closed circulatory system.
Has no true respiratory organs.
Reproduction normally sexual and gonochoristic or hermaphoditic.
Feed a wide range of material.
Live in most environments.

Meet Hirudo medicinalis;

Phylum Mollusca: Mollusca is one of the most diverse groups of animals on the planet (The Mollusca). It contains some of the most familiar invertebrates, including clams, slugs, snails, mussels, and octopuses (Mollusca). They are usually organisms with a sof body enlosed (most of the time, either partially or fully) in a calcium carbonate shell (Mollusk). Its main characteristics includes (The Phylum Mollusca);

Bilaterally symmetrical.
Body has more than two cell layers, tissues and organs.
Body without cavity.
Body possesses a through gut with mouth and anus.
Body monomeric and highly variable in form, may possess a dorsal or lateral shells of protein and calcareous spicules.
Has a nervous system with a circum-oesophagal ring, ganglia and paired nerve chords.
Has an open circulatory system with a heart and an aorta.
Has gaseous exchange organs called ctenidial gills.
Has a pair of kidneys.
Reproduction normally sexual and gonochoristic.
Feed a wide range of material.
Live in most environments

Meet Nototodarus sloanii;

Phylum Arthropoda: The most successful organisms on the planet for being able to dominate the world, representing more than 80% of the Animal Kingdom and probably at least half of all living organisms (Introduction to the Arthropoda). They include organisms like; centipedes, scorpions, spiders, crustaceans, and insects (Arthropoda (arthropods)). "All arthropods possess a stiff exoskeleton (external skeleton) composed primarily of chitin," (Arthropoda). They also have segmented bodies with bilaterally symmetrical bodies (Arthropoda (arthropods)). Its main characteristics includes (The Phylum Arthropoda);

Bilaterally symmetrical (in most cases).
Body has more than two cell layers, tissues and organs.
Body cavity a true coelom.
Most possesses a through straight gut with an anus (in most cases).
Body possesses 3 to 400+ pairs of jointed legs.
Body possesses an external skeleton (in most cases).
Body is divided in 2 or 3 sections.
Nervous system includes a brain and ganglia.
Possesses a respiratory system in the form of tracheae and spiracles (in most cases).
Possesses a open or lacunnar circulatory system with a simple heart, one or more arteries, and no veins, (in most cases).
Reproduction normally sexual and gonochoristic, but can be parthenogenetic.
Feed on everything.
Live everywhere.

Meet Latrodectus hasseltii;

Phylum Chordata: The most highly evolved phylum that includes humans and other vertebrates, however, not all chordates are vertebrates (Introduction to the Chordata). "As the name implies, at some time in the life cycle a chordate possesses a stiff, dorsal supporting rod (the notochord)," (Chordate). Its characteristics includes (Chordata (chordates));

bilateral symmetry
segmented body, including segmented muscles
three germ layers and a well-developed coelom.
single, dorsal, hollow nerve cord, usually with an enlarged anterior end (brain)
tail projecting beyond (posterior to) the anus at some stage of development
pharyngeal pouches present at some stage of development
ventral heart, with dorsal and ventral blood vessels and a closed blood system
complete digestive system
bony or cartilaginous endoskeleton usually present.

Meet Homo sapiens;

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