[LBBBIO8] Activity 10 Part 3

Phylum Cnidaria

• Greek

  • Knide = Nettle

  • Aria = Like/connected with

• Radial/biradial symmetry

• Most primitive of the eumetazoans (true multicellular animals)

• Dipoblastic

• Body form

  • 2-layered sac having a single internal coelenteron/gastrovascular activity

• Only 1 opening: Mouth (Also the anus)

• Nematocytes

• Cnidocytes

• Polymorphism

• Either monoecious or dioecious

• Aquatic animals

Epidermis

(Phylum Cnidaria)

• Dipoblastic

• Outer layer of cells

Inner gastrodermis

(Phylum Cnidaria)

• Dipoblastic

• Lines the gut cavity or gastrovascular cavity

• It secretes digestive juices into the cavity

Mesoglea

(Phylum Cnidaria)

Gelatinous matrix between epidermis and inner gastrodermis

• Noncellular jelly-like materials

Protoneurons

(Phylum Cnidaria)
Simplest animals to possess true nerve cells

Statocysts and ocelli

(Phylum Cnidaria)

Simplest animals to possess sense organs

Epitheliomuscular type

(Phylum Cnidaria)

Simplest animals to possess locomotory system

Nematocysts

(Phylum Cnidaria)
Only group of animals to have this organelle, used for defense and capturing prey

• Arms cnidocil with a stinging structure

Cnidocytes

(Phylum Cnidaria)

Specialized cells that contain and form the stinging organelles

Cnidocil

(Phylum Cnidaria)

Modified ilium in each cnidocyte

Polymorphism

Existence of more than one body form

Cylindrical polyp form

(Polymorphism)

• Sessile

• Tentacles encircling the mouth at the oral end

Medusa form

(Polymorphism)

• Umbrella/bell-like form

• Free swimming

• Mouth at the end of a manubrium

• Tentacles on the bell margin

Class Hydrozoa

• Solitary/colonial

• Polyp and Medusa

  • But 1 maybe suppressed in some species

• Relatively small and inconspicuous

• Freshwater or marine water

Polyps

(Class Hydrozoa)

Devoid of mesenteries

Medusae

(Class Hydrozoa)

Partially closed by a velum

Velum

(Class Hydrozoa)

Ingrowth or inward projections from the bell margin

Mesoglea

(Class Hydrozoa)

Noncellular

Gonads

(Class Hydrozoa)

Epidermal

Hydra

(Class Hydrozoa)

• Solitary

• Polyp without Medusa phase

• Pools, freshwater, and quiet streams

  • Attached underside of leaves

• Naked eye = 2 - 20 mm

• Cylindrical body resembling a tube

• Monoecious or dioecious

Mouth

(Hydra)

Oral/distal end

Hypostome

(Hydra)

• Mouth

• Can be found on a conical elevation

Tentacles

(Hydra)

• Mouth

• 6-10 slender, fingerlike, hollow projections

Foot / Basal disk

(Hydra)

Proximal/aboral end

• For attachment to a substratum

• Secretes gas bubble for floating

Bud

(Hydra)

• Asexual reproduction

• Hollow outgrowth from the body wall

Testis

(Hydra)

• Sexual reproduction

• Small ougrowth of the epidermis near the oral end

Ovary

(Hydra)

• Sexual reproduction

• Large, rounded elevation toward the basal end

Obelia

(Class Hydrozoa)

• Erect and bushy

• Colonial

• Sea

  • Attached to shells, rocks and algae/seaweed

• Resembles the end-result of a budding hydra

• Young medusa buds stacked on top of the other

Polyp form

(Obelia)

Seen by the naked eye

Medusa form

(Obelia)

Microscopic

Hydrocaulus

(Obelia)

Main stem

• Gives off side branches that are like hydra-like structures

Nutritive hydranths / Gastrozooids

(Obelia)

• Hydrocaulus

• Feeding polyps

Gonangia / Gonozooids

(Obelia)

• Hydrocaulus

• Reproductive polyps

Hydrorhizea

(Obelia)

Root-like structure

Perisarc

(Obelia)

Transparent, chitinous layer that covers the entire colony

Class Scyphozoa

• Solitary

• Coastal marine waters, some deep sea dwellers

• Medusa form: Most conspicuous stage

Medusa form

(Class Scyphozoa)

Its umbrella margin is scalloped/notched, velum absent, and larger than hydrozoan medusae

Polyp form

(Class Scyphozoa)

Absent, reduced, restricted to larval stage

Mesoglea

(Class Scyphozoa)

Thicker and cellular

Gonads

(Class Scyphozoa)

Gastrodermal

Aurelia

(Class Scyphozoa)

• Moon jelly

• Temperate and tropical sea waters

• Has semi-transparent umbrella, more discoidal, less cup-shaped than hydromedusae

Scyphomedusa

(Aurelia)

Solitary true jellysfish

Convex exumbrella

(Aurelia)

Upper / dorsal / aboral side

Concave subumbrella

(Aurelia)

Lower / ventral / oral side

Short tentacles

(Aurelia)

Fringe from around the animal’s umbrella margin

• Armed by nematocysts

Manubrium

(Aurelia)

• Tube-like extension that hangs down from the center of the subumbrella

• Square mouth opens at the end of it

• Drawn out to form 4 long, trough-like oral arms for capture and ingestion

Class Cubozoa

• Solitary

• Deadliest nematocysts

• Marine species

Polyp stage

(Class Cubozoa)

Reduced

Medusae

(Class Cubozoa)

Deep cup or bell - shaped, have four flattened sides and are square in cross sections

• Velum is absent

• Tentacles: Each corner of the bell margin bears 1 or more of it

Velarium

(Class Cubozoa)

Modified form of velum is present

Chironex

(Class Cubozoa)

Class Anthozoa

• Solitary or colonial

• Predominantly sessile

• Marine species

Polyp form

(Class Anthozoa)

Larger and complex

Medusa

(Class Anthozoa)

Absent

Flat oral disc bearing tentacles

(Class Anthozoa)

Contains the slit-like mouth leading to stomodaeum (pharynx), then to the coelenteron that divides into 8 mesenteries or septa with lidless nematocysts

Mesoglea

(Class Anthozoa)

Highly cellular and well developed

Gonads

(Class Anthozoa)

Endodermal

Order Scleractinia

• Stony corals

• Colonial or solitary

  • Colony forms delicate to massive calcareous

Acropora

(Order Scleractinia)

• Most abundant corals of most reefs of Indo-Pacific

• They outclass other corals in shallow tropical reefs

• Pale cream, brown or dark brown

Staghorn corals

(Acropora)

• Plate-like colonies that are branching and bushy

Corallum

(Acropora)

Colony is made up of nonliving exoskeleton of calcium carbonate

• Secreted by the polyps that resemble sea anemones

Corallite / Calyx

(Acropora)

Calcareous cup that encases each individual coral polyp

• Interconnected laterally

Skeleton

(Acropora)

Substratum for polyp, and protection where polyps can retract and hide from predators

Fungia

(Order Scleractinia)

• Mushroom corals

• Solitary and free-living

• Restricted to tropical waters and may occur in large concentration in equatorial regions

• Mushroom-shaped skeleton

• Diameter of 25 cm

• Flat / dom-shaped (Convex above and concave below) and Circular or elongate in outline

• Brown to pale brown

Sclerosepta

(Fungia)

Skeleton of this very large polyp is limited to it

• Projecting from the basal plate

Corallite

(Fungia)

No wall

Order Actiniaria

• Solitary with lacking calcareous skeleton

Metridium

(Order Actiniaria)

• Sea anemones inhabit the Pacific and Atlantic coasts, abundant in tropical areas

• Solitary, sessile animals

• Colorful animals

• Skin is soft and contains no skeletal structures

Cylindrical column form

(Metridium)

For the major part of the body

Oral disk

(Metridium)

The free end (Oral end) is differentiated into this flattened disk

Tentacles

(Metridium)

Oral disk bears several short, hollow tentacles

• Arranged in circlets around the central mouth

Gastrovascular cavity

(Metridium)

Slit-like mouth leads to short phraynx then into it

Siphonoglyphs

(Metridium)

Bears these deep, ciliated grooves at one or both ends

• Drive the water and its circulation into the G.C.

Basal / Pedal Disk

(Metridium)

Found at the opposite end of the colum

• Attaches the animal to a solid substrate

Order Antipatharia

• Numerous unpaired mesenteries

• Subclass include tube anemones and colonial black and thorny corals

Tentacles

(Order Antipatharia)

Simple and unbranched

Antipathes

(Order Antipatharia)

Order Alcyonacea

• 8 pinnate (branching tentacles

• 8 complete, unpaired mesenteries

Tentacles

(Order Alcyonacea)

Internal (an integral part of the tissue) of separate or fused calcareous spicules or of a horny material

Tubipora

(Order Alcyonacea)

• Organ-pipe corals

• Indo-Pacific

• Extensive clumps in shallow water

• Color red organ-like tubes of the skeleton

In situ

(Tubipora)

Brown to green tentacles of the polyps extending from the tubes obscure the red skeleton underwater

• Not easily recognized

Lack of choenchyme

(Tubipora)

This produces a creeping may of stolons from which polyps arise singly

Skeleton

(Tubipora)

Made up of long, upright, parallel calcareous tubes of fused spicules

Skeletal tubes

(Tubipora)

Encases and supports the polyps

Plates or platforms

(Tubipora)

Transverse calcareous where the tubes are connected at intervals

Sacrophyton

(Order Alcyonacea)

• Soft corals

• Tropical animals

• Indo-pacific reefs

• Soft, fleshy colonies

• 1 meter in diamter

Choenchyme

(Sacrophyton)

Forms a rubber mass and the colony may have a massive mushroom shape

Polyps

(Sacrophyton)

Embedded but restricted on the outer lobe of the fleshy choenchyme

• Where they retract and extend

Calcareous spicules

(Sacrophyton)

Scattered and embedded in choenchyme