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Home , Cnidocyte, Coelenterata, Gastrovascular cavity, Helioporacea, Hydra (genus), Octocorallia

Hydra, , , & sea anemones I. radial symmetry

II. dimorphic development

III. nematocysts, specialized produced by Radial

Compass jellyfish General Characteristics

• They are radially symmetrical; oral end terminates in a mouth surrounded by .

• They have 2 tissue layers

• Outer layer of cells - the epidermis

• Inner gastrodermis, which lines the gut cavity or gastrovascular cavity (gastrodermis secretes digestive juices into the gastrovascular cavity)

• In between these tissue layers is a noncellular jelly-like material called mesoglea Characteristics • Diploblastic – Epiderm & hypoderm Polymorphism : more than one body form

1.

2. Medusa Cnidarian Body Plans

Polyp form • Tubular body, with the mouth directed upward. • Around the mouth are a whorl of feeding tentacles. • Only have a small amount of mesoglea • Sessile

Medusa form • Bell-shaped or umbrella shaped body, with the mouth is directed downward.

• Small tentacles, directed downward.

• Possess a large amount of mesoglea • Motile, move by weak contractions of body Forms of Cnidarians Polyp

• tentacles around the mouth • Sessile Polyp () Polyp () Medusa

• Umbrella shape • Tentacles around mouth • Motile, Free-swimming

Dimorphic Life Cycle

Colonial hydrozoan Tentacles

• Have nematocysts (stinging cells)

• Coiled thread discharges like a harpoon

• Contains neurotoxin

• Paralyzes prey Stinging Organelles

• Prey capture is enhanced by use of specialized stinging cells called cnidocytes located in the outer epidermis.

• Each has a modified cilium - cnidocil, and is armed with a stinging structure called a nematocyst.

• The undischarged nematocyst is composed of a long coiled thread

• When triggered to release, either by touch or chemosensation, the nematocyst is released from the cnidocyte and the coiled thread is everted

• Some nematocysts function to entangle the prey; others harpoon prey and inject a paralyzing

Discharged nematocyst Hydrazoan stinging and capturing prey Habitat Aquatic

 Most Marine

 Few fresh-water Feeding Carnivores (predators) Process of feeding

1. Tentacles sting prey with nematocysts

2. Tentacles grab prey

3. Prey pulled into mouth

4. Prey stuffed into gastro-vascular cavity (GVC)* Lion’s mane eats another jelly

5. GVC makes enzymes, extra-cellular digestion

6. Undigested food back out mouth

*incomplete digestive tract (no anus) Digestive System Nutrition

• Cnidarians are carnivores with hydras and consuming and some of the sea anenomes consuming small fishes

• They use tentacles to capture prey and direct it toward the mouth so that it can be digested in the gastrovascular cavity via secretions from gland cells (); some food is phagocytized by special cells and digestion occurs intracellularly

• The gastrovascular cavity exists as 1 opening for food intake and the elimination of waste

• There is no system of internal transport, or excretion; all these processes take place via diffusion Respiration

• Via diffusion Excretion

• Via diffusion Response

Sensory cells

1. (chemicals)

2. Thigmoreceptors (touch)

3. Photoreceptors (light)

Ocelli (eyespots)

4. Statocysts (balance) Locomotion

A. Medusa motile, free-swimming

A. Polyps sessile

Exceptions:

1. Hydra tumbles on tentacles

2. Sea anemones glide on pedal disc

1. Asexual budding from polyps or medusa

2. Sexual a. Medusae release sperm & eggs b. Some monoecious, some dioecious

 Larvae free-swimming Cnidarian

Phylum:

Cnidaria: (formerly called )

Class:

I. : (hydroids) II. : (jellyfish) III. : (corals) Class Hydrozoa: The Hydras

• Polyp phase is dominant : Cnidaria

Class: Hydrozoa: (hydroids)

 the most part colonial that have alternating medusa and polyp stages

 This order has a chitinous exoskeleton

 Hydrozoa are colonial and create an aragonite ( carbonate based) skeleton

 The best known of these complex colonial organisms is the Portuguese man-of-war (Physalia physalis). Colonial Hydrozoans • Fire Corals – NOT TRUE CORAL • Hydrozoan

– TRUE CORAL • Anthozoan colony Phylum: Cnidaria: (formerly called Coelenterata)

Class:

Scyphozoa: (Jellyfish)

The class Scyphozoa is generally characterized by having a much larger medusa stage than polyp stage

Scyphozoan Life Cycle (Moon jelly) Class Anthozoa Class Anthozoa: Anemones & Corals

• Appear like plants but are .

• Polyp form is dominant.

Anemone • Corals build calcium shells to protect themselves

• Have symbiotic relationship with .

• Can build extensive masses which can form land masses.

Coral Polyps Class Anthozoa • Exclusively marine; there is no medusa stage • At one or both ends of the mouth is a ciliated groove called the siphonoglyph; generates a water current and brings food to the gastrovascular cavity

• Possess a well developed pharynx • The gastrovascular cavity is large and septa or mesenteries; increase surface area for digestion or support Class Anthozoa

Corals obtain much of their energy from microscopic photosynthetic algae (zooxanthellae) or dinoflagellates that live symbiotically inside the cells of the coral

Zooxanthallae is a among the Dinoflagellata

It will loose its flagella and live in the tissue of corals Phylum: Cnidaria

Class: Anthozoa: (corals)

 In general, the class is comprised of the vast majority of species commonly referred to as sea anemones and corals.

 existing exclusively as polyps, completely without a medusa life stage

 Anthozoa into three subclasses:

I. ,

II. ,

III. Ceriantipatharia Class: Anthozoa: (corals) Sub class: Octocorallia (Soft corals)

 Octocorallia: commonly known as soft corals

 not very closely related to the true corals ()

 The polyps of octocoralliarians have eight tentacles

 divided into five or six orders (Telestacea, , Gorgonacea, Pennatulacea, , and sometimes Stolonifera)

Tubipora musica () :

Menella sp. Family Plexauridae :

Dendronepthya sp. Kukenthal, 1905

Colony shape: bushy

Habitat : depth above 10 , with clear water ( visibility 8 m) Family Plexauridae :

Echinomuricea sp. Verrill,1869 Class: Anthozoa: (corals) Sub class: Octocorallia

 Most do not develop skeletons

 Most octocorals form spicules within their tissues, and some produce calcified holdfast structures or long, rodlike internal supports.

 All of the octocorals are colonial, including the sea fans and sea whips (Gorgonacea). Class: Anthozoa: (corals) Sub class: Hexacorallia Order: Scleractinia (True Stony Corals)

 The scleractinians are the largest group of anthozoans, with approximately 3600 extant species

 This prominent taxon provides the calcium carbonate building blocks for the world’s coral reefs

 calcium carbonate skeleton is secreted by the epidermis and is present in all members of this order

 The order Scleractinia is usually divided into 18 families Class: Anthozoa: (corals) Sub class: Hexacorallia Order: Scleractinia (True Stony Corals)

 Scleractina are classified by morphological features of colony growth and various soft-tissue features

 The Acroporidae are mostly in two genera, and . These are fast-growing forms with both asexual and .

 Some scleractinians, like members of the genus , are solitary and can be relatively large: up to 50 cm in diameter

Acropora nasuta Montipora capricornis Fungia Class: Anthozoa: (corals)

Sub class: Hexacorallia

Hexacorallia is comprised of six orders, two of which are extinct, order Rugosa and .

I. order: Actinaria : sea anemones

II. order: Zoanthidia : colonial anemones Class: Anthozoa: (corals) Sub class: Hexacorallia Order: Actinaria (sea anemones)

I. Most of the soft-bodied anthozoans known as sea anemones are classified in the Actinaria

II. Actinarians generally have column-shaped bodies with the mouth at one end and a muscular pedal disk for attachment to substrates at the other.

I. Actinarians have soft bodies and do not form hard parts, some coat themselves with sand grains and/or mucuslike secretions. Sea Anemones (with sea urchins) Class Anthozoa: Sea Anemones Class: Anthozoa: (corals) Sub class: Hexacorallia Order: Actinaria (sea anemones)

I. Most actinarians are relatively sessile, either not moving or moving very slowly by contractions of the pedal disk

II. Some anemones burrow into sand, and a few can swim short distances

III. Actinarian anemones can reproduce either sexually or asexually

IV. They do not form true colonies with permanent tissue connections between members, as seen in the superficially similar zoanthiniarian anemones

Class: Anthozoa: (corals) Sub class: Hexacorallia Order: Zoanthidia

 Small group of polypoid anthozoans that differ from most sea anemones (Actinaria) in details of internal .

 unlike most sea anemones, zoanthiniarians can form true colonies in which all members are connected by common tissue.

 Zoanthiniarians make no hard parts and leave no fossil record

 However, they are more closely related to extinct coral taxa (Tabulata and Rugosa) than they are to other soft-bodied anthozoans Genus: Zoanthus Class: Anthozoa: (corals) Sub class: Hexacorallia Order: Zoanthidia Sub order: Brachynemina Family: Zoanthidae Genus: Zoanthus

 This taxon is often referred to as intermediate in form between hard corals (Scleractinia) and sea anemones (Actiniaria), as most species lack a skeleton and yet are colonial.

 Zoantharians are widely distributed and are particularly common in subtropical and tropical regions, where they are one of the major benthic components of coral reefs.

 Some species contain unique chemicals such as palytoxin or norzoanthamine Genus: Zoanthus

Where seen?

 Like a carpet of tiny flowers, these animals are often seen on:

I. shores, II. growing on stones III. as well as under seagrasses in vast seagrass meadows. IV. They may form a dense carpet that covers large areas of several square metres Genus: Zoanthus

What do they eat?

 Zoanthus spp. do not need to be fed directly, since they obtain much of their nutritional requirements from their symbiotic zooxanthellae.

 They must therefore be provided with adequate illumination to thrive.

 They also ingest dissolved organic substances from the water, as well as fine particulate matter.

 Some species do not take large particles of food, while others do take and eat such things as flake food, blackworms, shrimp, and sea urchin eggs. Genus: Zoanthus

 Zoanthids mainly reproduce asexually, although there is a limited amount of sexual reproduction

 Zoanthids differ from true sea anemones, which belong to the subclass Actiniaria, based on details of their internal anatomy and the fact that zoanthids form true colonies in which the individual polyps are connected by a common tissue, the coenenchyme. Genus: Zoanthus

 Members of this genus are the most colourful of the zoanthids, being shades of green and brown typically, but sometimes fluorescent red, orange, pink, blue, yellow, or gray, and usually two-toned Genus: Zoanthus

 These Anthozoans consist of a skeleton made from detritus and sand particles which is not hard enough to sustain the currents, but it definitely helps in forming huge colonies in areas with high sediment rates.

 The zoanthids form a major constituent of the rocky intertidal macro benthos

 Zoanthus sp. have soft bodies covered with a leathery skin, called the cuticle, which gives them protection.

 Their polyps have fairly short stalks topped with a small flat oral disc.

 Tentacles radiate from the outside of the oral disc and are usually expanded day and night. Morphological and Genetic studies of Zoanthid Genus Zoanthus in some coral islands of the Persian Gulf: Qeshm, Larak and Kish

Atoosa Noori Koupaei* , Pargol Ghavam Mostafavi , Jalil Fallah Mehrabadi , Seyed Mohammad Reza Fatemi

 The results of the present study show that the nucleotide sequence of this mitochondrial fragment is identical in all the examined samples and is consistent with the reported sequences of the species of Zoanthus sansibaricus.

 What this study obtained is undoubtedly a systematic report from the color variation of the available samples in the Iranian islands of the Persian Gulf. Observation of brown, green, gray, red, pink and purple polyps, green and brown tentacles, green, red, blue and pink oral color with oral disc green, red, blue, pink and gray colors confirms a wide range of colors in this species.  In this study, diversity of shallow water zoanthids off the Qeshm Island, the largest island in the Persian Gulf, was investigated for the first time.

 Using in situ field examination integrated with 16S rDNA sequencing and phylogenetic analysis

 the presence of three zoanthid species in the inter-tidal and shallow water zone of Qeshm Island were demonstrated Zoanthus sansibaricus (n = 12) with five morphotypes,

Palythoa tuberculosa (n = 4) with just one morphotype.

Palythoa cf. mutuki (n = 10) with two morphotypes

Natural Products Isolated from the Order

1. Zoanthusterone : is a representative ecdysteroid isolated from a Zoanthus

2. Prostaglandins like PGA2 : isolated from Palythoa

3. zoanthoxanthin: natural products based on the highly fluorescent

4. parazoanthoxanthin A : has shown significant anticholinesterase activity

5. Palytoxin