Invertebrates

1. Groups

Phylum

General Characteristics

Sponges

Porifera

Germ Layer-None; Symmetry-None; Body Plan-None; Coelom-Acoelomate; Segmentation-None. Sponges; about 5,000 aquatic, mostly marine, grow singly or in a colony; species of asymmetrical animals that lack distinct tissues and organs; body consists of two layers supported by a stiff skeleton; tube, cup, or barrel shape; sponges are aquatic, mostly marine, and sessile; reproduction sexual or asexual (hermaphroditic). Overall appearance varies widely. Calcarea (calcium carbonate spicules), Hexactinelllida (glassy spicules), Demospongiae (varied spicules of sponging, glassy or combination).

Cnidarians

Cnidaria

Germ Layer-Two; Symmetry-Radial; Body Plan-Sac; Coelom- Acoelomate; Segmentation-None. Jellyfishes, sea anemones (flowers of the ocean), corals, Hydra, Obelia, - 9,000 species; radially symmetrical; gastrovascular digestive cavity with only one opening (fluid serves as hydrostatic skeleton; two body layers separated by jellylike mesoglea; tentacles armed with stinging cells; two body life cycle forms (may include just one or the other): vase-shaped polyp (asexual) and bell-shaped medusa (sexual); sac body plan with mouth serving as both in and out opening; live singly or in colonies often made up of specialized individuals; reproduction sexual or asexual; nerve network below epidermis; stinging cell (cnidocytes) contain capsules (nematocysts) with barbed or poisonous thread to capture pray or for defense. Class Scyphozoa contains true jellyfishes.

Ctenophors

Ctenophora

Germ Layer-Two; Symmetry-Radial; Body Plan-Sac; Coelom- Acoelomate; Segmentation-None. Sea walnut and comb jellies; about 90 species; small, translucent, gelatinous marine animals with eight bands (rows) of fused cilia; whiplike tentacles; often bioluminescent. Two anal pores; third tissue layer between the endoderm and ectoderm; swim or creeps on bottom of sea; love on other animals such as echinoderms, sponges or benthic cnidarians. Emit bluish-green light when disturbed.

Flatworms

Platyhelminthes

Germ Layer-Three; Symmetry-Bilateral; Body Plan-Sac - Organs; Coelom- Acoelomate; Segmentation-None. Planarians, flukes, tapeworms, about 13,000 species; bilaterally symmetrical with three germ layers (middle layer is mesoderm gives rise to parenchyma and muscles; digestive cavity has only one opening; no circulatory or respiratory systems; no coelom or pseudocoelom; organs for digestion, excretion, sexual and asexual reproduction, and nerve conduction; sac body plan with mouth serving as both a mouth and anus (there is no anus). Cephalization: Planarians have a definite head with sense organs. Eyespots, auricle, pharynx, and gastovascular cavity.

Roundworms

Nematoda

Germ Layer-Three; Symmetry-Bilateral; Body Plan-Tube-within-tube; Coelom-Pseudocoel; Segmentation-None. Ascaris; - 12,000 species: mostly parasitic species; tubular and bilaterally symmetrical body form; digestive tract has two openings; pseudocoelom; found in aquatic and damp soils, hot springs, deserts, cider vinegar; parasitize plants and animals; crop pest and human disease; trichinosis and elephantiasis caused by roundworms; organ level organization, three germ layers, bilateral symmetry; tub in tube body plan; digestive tract has both a mouth and an anus; pseudocoelom body cavity with space for organs lined with mesoderm; have brain plus dorsal, ventral and lateral nerves; non-segmented body wall is smooth and not divided into segments; reproduction sexual (dioecious).

Rotifers

Rotifera

Germ Layer-Three; Symmetry-Bilateral; Body Plan- Tube-within-tube; Coelom- Pseudocoel; Segmentation-None. Rotifers- 2,000 species; freshwater rotifers or �wheel� animals; wormlike or spherical; complete digestive tract; crown (corona) of cilia on anterior end resembling a wheel for locomotion and feeding. Has mouth, brain, stomach, pharynx, muscle, bladder, intestine, ovary, anus, flame cell, cuticle, cement gland in toe, dorsal sensory projection, eye. Sexual or asexual. Brachionnus; Monogononta, Bdelloidea, and Seisonidea

2. Groups	Phylum	Primitive Features
Sponges	Porifera	Multicellular organisms, but they have no true tissues. Primitively, they show radial symmetry.
Cnidarians	Cnidaria	These organisms have endoderm and ectoderm (and retain the radial symmetry they inherited from their common ancestor with sponges), but they have a blind gut and no coelom. Cnidarians are also the most primitive animals that digest their food in an internal body cavity, a simple blind pouch called a gastrovascular cavity or GVC for short. Food is stuffed into the GVC by the tentacles that fringe the mouth. Gland cells lining the GVC secrete digestive enzymes into the pouch to break up the food into particles small enough for the cells lining the GVC to absorb. Thus, unlike more primitive animals, they can eat things that are bigger than a single cell.
Ctenophors	Ctenophora	Comb jellies (Phylum Ctenophora; fr. Gr. cten = comb, phoros = to bear) used to be classified with the Cnidarians, but later research revealed that the resemblance between comb jellies and true jellyfish was only superficial. For example, they usually lack cnidocytes, and catch their prey with sticky cells that line their tentacles. In life they are among the most beautiful organisms on Earth.
Flatworms	Platyhelminthes	Flatworms are commonly found in marine and freshwater habitats, moving along the undersides of underwater rocks, leaves or sticks. Feeding flatworms extend a long pharynx out of their mouths. This tube leads directly into the digestive tract. The intestine is a simple sac with one opening. Two large branches run down the length of the body. Side branches of this gut cavity reach almost all of the clusters of cells in the flatworm's body.
Roundworms	Nematoda	They are round, bilaterally symmetric and pseudocoelomate, with a toughened cuticle, an outer layer that protects the parasitic forms against digestive enzymes. The basic body shape seems to be an adaptation for living in interstitial habitats, the small spaces between grains of sand. Nematode worms lack circular muscles. They only have longitudinal muscles, and thus appear to thrash about aimlessly. This type of motion appears rudderless. We see them free floating in water or vinegar (Tubatrix), but works very well in their usual interstitial habitat, where there are plenty of packed grains of soil to push against and wriggle through.
Rotifers	Rotifera	Rotifers are very widespread aquatic animals, very common in freshwater habitats. We usually overlook them because they are so small, about 0.04 to 2 mm in size, not much larger than a big protozoan. They are very abundant, with about 1,000 rotifers in a typical liter of freshwater habitat. Rotifers are pseudocoelomate, with a complete digestive tract, and a muscular pharynx or mastax, which they use to grind their food. They feed by means of a crown of cilia called a corona, which beat together to draw water over the mouth. This tuft of cilia gives them their common name "wheel animals". Rotifers have a primitive eye cup, like the flatworm, and other primitive senses tied into a rudimentary brain. They can be either sessile suspension feeders, filtering out tiny protozoans and algae, and bits of detritus, or raptorial, animals that actively pursue their tiny prey. A few species are parasitic. They only reproduce sexually, and have separate sexes. Most are parthenogenetic, unfertilized eggs can develop directly into female adults. They copulate by means of "hypodermic injection". These strange little animals are a very important link in the food chain in aquatic environments. They may have evolved from flatworms, because they share many basic features, such as flame cells, a similar pharynx, and numerous cilia.

Organism	Phylum	Class
Sponge, Venus Flower Basket	Porifera	Hexactinella
Colenterates, Hydra	Cnidaria	Hydrozoa
Comb Jellies	Ctenophora
Flatworm, Flukes	Platyhelminthes	Trematoda
Roundworms	Nematoda
Shallow water sponge	Porifera	Calcarea
Deep water sponge	Porifera	Hexactinella
Jellyfish	Cnidaria	Scyphozoa
Sea anemones	Cnidaria	Anthozoa
Tapeworms	Plathelminthes	Cestoda

Feature	Function	Group that possesses this feature
spicules	Endoskeleton - Needle-shaped skeletal elements in sponges that occur in the matrix between the epidermal and collar cells.	Porifera
gastrovascular cavity	Digestive system - A coral may consist of a single polyp or a colony of thousands of polyps that are linked by a common gastrovascular system through which they share food, water, and wastes with surrounding polyps.	Cndaria, Platyhelminthes
eyespots	Light photosensitive sensory organ	Platyhelminthes, Rotifera
tentacles with nematocyst (cnidocytes)	Food capturing device- The stinging cell consists of a capsule with a sensory hair, a lid, and an interior nematocyst which actually stings, captures, and subdues prey	Cnidaria
amoeboid cells	Transport food - Amoeboid cells in sponges that occur in the matrix between the epidermal and collar cells. They transport nutrients.	Porifera
pores	Water input openings for food filtering	Porifera
osculum	Water output openings for food filtering - in sponges, the external opening of an excurrent canal.	Porifera
pharynx	Digestive tube portion � sucks up food with muscular tube posterior to the mouth.	Platyhelminthes, Rotifera
corona	Crown of cilia draws water over mouth to obtain food.	Rotifera
auricles	A lateral projection which contains nerve endings sensitive to touch and to chemicals.	Platyhelminthes
medusa and polyp stages	Two different phases of life.	Cndaria
foot	Organ for locomotion or holding a position. Rotifers have a foot attached to their posterior end and it includes a cement gland in a toe.	Rotifera
collar cells	Maintains a flow of water through the sponge by beating a flagellum that extends into the inner canal.	Porifera

Image 1

1.    Phylum: Cnidaria
2.    Common names : Sea anemones
3.    symmetry : Radial
4.    body plan : Sac body � tissue - plan
5.    How does it capture its food? : Their tentacles contain the stinging cells called nematocysts. The stinging cell consists of a capsule with a sensory hair, a lid, and an interior nematocyst which actually stings, captures, and subdues prey. When the sensory hair is triggered by another animal's movement, the nematocyst fires from the capsule, much like a harpoon.

Image 2

1.    Phylum : Nematodes
2.    Name : Ascares - Roundworms
3.    Two primitive features :   Tube-within-a-tube with a mouth and anus
4.    Symmetry : Bilateral

Image 3

1.    Phylum: Porifera
2.    How do it get its food: Filters water through pores � intracellular digestion by amoeboid cells.
3.    Symmetry: Asymetrical
4.    Internal skeleton: The major structural protein in the animal kingdom is collagen,* and fibrils of collagen are found throughout the intercellular matrix of all sponges. Additionally, the skeleton can be composed of spicules* of silica or calcium carbonate, or of fibers of an elastic protein called spongin* .

Image 4

1.    Phylum : Cnidaria
2.    symmetry : Radial
3.    How does it get it food? : Gastrovascular
4.    Exoskeleton made of what material? : Calcium carbonate (limestone)

Image 5

1.    Phylum : Platyhelminthes (flatworm)
2.    Class : Turbellaria
3.    Primitive features : Eye cup
4.    What organ systems does this organism have? : Digestion, excretion, nerve conduction, sexual and asexual, mouth, brain, eyespots, auricle, pharynx, and gastrovascular cavity.
5.    Symmetry : Bilateral

Image 6

1.    Phylum: Rotifera
2.    Label A function: Corona � Crown of cilia draws water over mouth to obtain food.
3.    Primitive feature: Eye cup
4.    Another phylum with the same primitive feature: Flatworm; Platyhelminthes

STUDY MATERIAL

Kingdom Animalia

SubKingdom Parazoa (partial phylum list)

Phylum Porifera (Sponges) (Grantia, Spongilla, Euplectella)

Class Calcarea (Calcium carbonate spicules)
Class Hexactinellida (Glass silica spicules)
Class Demospongiae (Spicules are siliceous but not six-rayed)
Class Sclerospongiae

Phylum Cnidaria

Class Hydrozoa (�Fire corals�) (Hydra, Obelia, Physalia,)
Class Cubozoa (Sea wasps � deadly)
Class Scyphozoa (True jellyfish)
Class Anthozoa (Corals, sea anemones, sea fans)

Phylum Ctenophora

Phylum Platyhelminthes

Class Turbellaria (Flatworms) (Planaria)
Class Trematoda (Flukes) (Chlonorchis, Schistomsoma)
Class Cestoda (Tapeworms) (Taenia, Diplidium)

Phylum Nemertea (Ribbonworms)

Class Anopla (Ribbonworms)
Class Enopla (Ribbonworms)

Phylum Nematoda (Roundworms) (Ascaris, Tubatris [vinegar eels])

Class Adenophorea
Class Secernentea

Phylum Rotifera (rotifers) (Philodina)

Class Seisonidea (two species) (Seison nebaliae, Seison annulatus)
Class Bdelloidea
Class Monogonota

Phylum Annelida

Class Hirudinea (Leeches)

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1. Groups	Phylum	General Characteristics
Sponges	Porifera	Germ Layer-None; Symmetry-None; Body Plan-None; Coelom-Acoelomate; Segmentation-None. Sponges; about 5,000 aquatic, mostly marine, grow singly or in a colony; species of asymmetrical animals that lack distinct tissues and organs; body consists of two layers supported by a stiff skeleton; tube, cup, or barrel shape; sponges are aquatic, mostly marine, and sessile; reproduction sexual or asexual (hermaphroditic). Overall appearance varies widely. Calcarea (calcium carbonate spicules), Hexactinelllida (glassy spicules), Demospongiae (varied spicules of sponging, glassy or combination).
Cnidarians	Cnidaria	Germ Layer-Two; Symmetry-Radial; Body Plan-Sac; Coelom- Acoelomate; Segmentation-None. Jellyfishes, sea anemones (flowers of the ocean), corals, Hydra, Obelia, - 9,000 species; radially symmetrical; gastrovascular digestive cavity with only one opening (fluid serves as hydrostatic skeleton; two body layers separated by jellylike mesoglea; tentacles armed with stinging cells; two body life cycle forms (may include just one or the other): vase-shaped polyp (asexual) and bell-shaped medusa (sexual); sac body plan with mouth serving as both in and out opening; live singly or in colonies often made up of specialized individuals; reproduction sexual or asexual; nerve network below epidermis; stinging cell (cnidocytes) contain capsules (nematocysts) with barbed or poisonous thread to capture pray or for defense. Class Scyphozoa contains true jellyfishes.
Ctenophors	Ctenophora	Germ Layer-Two; Symmetry-Radial; Body Plan-Sac; Coelom- Acoelomate; Segmentation-None. Sea walnut and comb jellies; about 90 species; small, translucent, gelatinous marine animals with eight bands (rows) of fused cilia; whiplike tentacles; often bioluminescent. Two anal pores; third tissue layer between the endoderm and ectoderm; swim or creeps on bottom of sea; love on other animals such as echinoderms, sponges or benthic cnidarians. Emit bluish-green light when disturbed.
Flatworms	Platyhelminthes	Germ Layer-Three; Symmetry-Bilateral; Body Plan-Sac - Organs; Coelom- Acoelomate; Segmentation-None. Planarians, flukes, tapeworms, about 13,000 species; bilaterally symmetrical with three germ layers (middle layer is mesoderm gives rise to parenchyma and muscles; digestive cavity has only one opening; no circulatory or respiratory systems; no coelom or pseudocoelom; organs for digestion, excretion, sexual and asexual reproduction, and nerve conduction; sac body plan with mouth serving as both a mouth and anus (there is no anus). Cephalization: Planarians have a definite head with sense organs. Eyespots, auricle, pharynx, and gastovascular cavity.
Roundworms	Nematoda	Germ Layer-Three; Symmetry-Bilateral; Body Plan-Tube-within-tube; Coelom-Pseudocoel; Segmentation-None. Ascaris; - 12,000 species: mostly parasitic species; tubular and bilaterally symmetrical body form; digestive tract has two openings; pseudocoelom; found in aquatic and damp soils, hot springs, deserts, cider vinegar; parasitize plants and animals; crop pest and human disease; trichinosis and elephantiasis caused by roundworms; organ level organization, three germ layers, bilateral symmetry; tub in tube body plan; digestive tract has both a mouth and an anus; pseudocoelom body cavity with space for organs lined with mesoderm; have brain plus dorsal, ventral and lateral nerves; non-segmented body wall is smooth and not divided into segments; reproduction sexual (dioecious).
Rotifers	Rotifera	Germ Layer-Three; Symmetry-Bilateral; Body Plan- Tube-within-tube; Coelom- Pseudocoel; Segmentation-None. Rotifers- 2,000 species; freshwater rotifers or �wheel� animals; wormlike or spherical; complete digestive tract; crown (corona) of cilia on anterior end resembling a wheel for locomotion and feeding. Has mouth, brain, stomach, pharynx, muscle, bladder, intestine, ovary, anus, flame cell, cuticle, cement gland in toe, dorsal sensory projection, eye. Sexual or asexual. Brachionnus; Monogononta, Bdelloidea, and Seisonidea

Light photosensitive sensory organ

Water input openings for food filtering

Digestive tube portion � sucks up food with muscular tube posterior to the mouth.

Kingdom Animalia