Marine Biology Exam 2

Dr. Traci Erin Cox's Marine Biology at LSUNO

Phylum Cnidaria

• Have Ecto & Endo Derm tissue layers

• Often Radial Symmetry (oral - aboral body axis)

• Stinging/Adhesive structured called cnidocytes containing nematocysts cells

• Exhibit alternation of asexual polypoid & sexual medusoid generations

• SImple Nerve Net nervous system

• Have Planula Larvae

• Osmoregulation through body wall

Cnidaria Body Plan

• Poses a medusa, polyp or both.

• Mesoglea from ectoderm

• Tentacled & a mouth lead to gastrovascular cavity that responsible for digestion and circulation

• Have a Hyrdrostatic Skeleton (water supported)

Cnidocyte aka Nematocysts

Cnidocil is triggered - the operculum opend and the coiled shaft is everted exposing stylet w spines- may have stinging toxins released

How to Cnidaria Feed?

• Carnivores or parasites that use tentacled to capture food and bring to mouth (some w oral disk that closes on food) use a mucus net suspension feeding

• Have a symbiotic relationships with zooxanthellae and digest extracellularly

Class Anthozoa - Phylum Cnidaria

• Anemones, corals, sea pens and sea pansy (exclusively marine)

• Lack Medusa stage ARE Benthic Polyps most w 8 tentacles

• Gastrovascular cavity lined w ciliated ,cnidae & gland cells called mesentary filaments (string-like internal tissue folds that corals can extend out of their mouths to digest food, clean surfaces, or attack neighboring competitors)

• Pharynx is a flagellated groove

• Polyps thats reproduce xesually and asexually (releasing gametes thru cavity)

Anemone Structure- Anthozoa - Cnidaria

Acontia are filaments that are used in defense and feeding … may have defensive structures around oral tentacles to fight with neighbors

Individual polyps in a colony are called zooids which connect thru the mesoglea

Two Types of Coral

• Those that build reefs are called Hermatypic- these harbor zooxanthellae (symbiodium)

• Ahermatypic corals lack zooxanthellea and fully rely on capturing food (can also be solitary)

Direct / Vertical Transfer Coral (anthozoa) Symbionts

Asexually = symbiont released in egg from mother or are obtained thru phagocytosis from the coral or be infiltrated by the zooxanthellae containing cytoplasmic extensions of the coral cells

Indirect / Horizontal Transfer of Coral (Anthozoa) Symbionts

Are absorbed by environment motile zooxanthellae can show positive chemotaxis in the direction of corals with zero or lower concentrations of zooxanthellae

Corals can obtain zooxanthellae indirectly through the ingestion of fecal matter excreted by corallivores.

Class Scyphozoa - Phylum Cnidaria

• True Jellyfish (exclusively marine) cane be both benthic and planktonic bc of medusa and polyp life stages (may even lack polyp stage)

• Medusa stage is large - Polyps are small, inconspicuous & can be long lived

• Polyps produce Medusa throu asexual budding called strobilation

• Have THICK mesoglea

• Medusas move by moscular contraction of the bell

Scyphozoa Structure

Scyphozoa Reproduction

Class Hydrozoa - Phylum Cnidaria

• Hydrozoids

• Usually colonial & polymorphic Polyps

• Medusa and Polyps can be present

• Reproduction involves medusa usually involved in production of gametes & polyp asexual budding

• Medusa can be retained on polyp

• Medusa has a structure called a velum that tends to be clear

• Protein exoskeleton usually chiton called a perisarc and living tissue called coenosar

Siphonores - Class Hydrozoa - Phylum Cnidaria

• Domain Eukarya , Kingdom Animalia .. Order Siphonophorae

• Are polymorphiv swimming/floating colonies with number of distinct polyp types & attached modified medusae. Most have gas filled flotation zooids

• Some deep sea species have bioluminescent lures to help engulf their prey

Zooids

Individuals within the colonies that perform different functions.

The 3 Body Plans of Siphonores

• Pneumatophore -gas filled to float

• Nectosome - Region of body specialized for moving colony through the water - contract in coordination propelling colony forward

• Siphonsome- all other polyps: feeding, reproductive, excretory and defensive polyps

Class Cubozoa- P: Cnidaria K: Animalia D:Eukarya

• Colorless Medusas 1-30 cms. Bell square in cross sections w eyes. Strong swimmers in tropical seas

• Sexual reproduction w/o strobilation

• Highly toxic Nematocysts in cnidae,

Sensory systems in Jellies & Cubozoas

• Cubozoans have inner nerve-ring VS jellies tend to have non-centralized nerve net

• Rhopalia - small, club-shaped sensory organs found along the bell margins of Scyphozoan and Cubozoan ( who have the more advanced type w eye receptors)

Cubozoans behavior: see & swim

• Rapidly change motion w visual stimuli

• Each Rhopalia has 3 sets of eyes: pit shaped pigment eyes, slit shaped pigment eyes, camera type eyes w cornea, lens & retina

• Many sensory cells in each eye w big neurons hear rhopalia - other cnidaria have statoliths

Phylum Ctenophores (Comb jellies) K: Animalia D:Eukarya

• 2 tissues layers: ectoderm & endoderm w biradial symmetry w ab/oral axis. Gastrovascular cavity with 8 rows of cilliary plates called combs

• have structure called colloblasts, adhesive for prey capture. pair of retractable tentacles.

• More complex of a nerve net compared to cnidarians

• Monomorphic w no alternate life stages buttt have larval stages called cydippid

Body Plan of Ctenophores

Ctenophore Movement

• Pelagic - Neutral Buoyancy: Use ctenes beats to move

• Ctenes densely packed making them iridescent - hydrostatic skeleton with mesenchymal musculature

• Flap oral lobes but one species creates a vortex wake w the ctenes creating jet propulsion

Ctenophores Feeding

• Colloblast adhesive to prey. Mixed Diet of microplankton or macrozooplankton

• Digestion extracellular in the pharynx & broken down food gets passed down in canals, exits 2 small anal pores

Waste Management of Ctenophores

• Diffusion for osomregulation, gas exhange, circulation etc

• Gastrovascular cavity aides in these functions + Ctenes beats

Statocysts

• Apical sense organ used for balance and orientation (simple nerve center) coordanates the comb rows

Cteneophore Reproduction

• reproduce through gametes & can shed them through their mouth. Fertilization takes place in the water column or in the canals. Producing Cydippid Larva aka a feeding larvaw that are planktotrophic

• Regenerate lost parts

Phylum: Platyhelminthes ,Clade Bilateria (Flatworms thru anthropods)

• Flat Worms: 75% Parasitic w free living ones being marine/freshwater benthic

• Unsegmented, dorsally flattened

• Have Spiral Cleavage and are protostomes

• Lack a coelem ( =acoelomate)

• Are Triblastic- have 3 tissue layers

• Cephalized w a simple nervous system

• Hemaphroditic w complex reproductive system.

• Have Protonephiridia for osmoregulation/excretory function

Protonephidria

• Simple network-like excretory/osmoregulatory organs found in flatworms, nemerteans, rotifers and lancelets

Coelem

• a fluid-filled body cavity in most triploblastic animals; its completely lined w tissue derived from embryonic layer. It separates gut from outer body wall, giving organs room to function. (Platyhelminthes lack them)

Spiral Cleavage

Growth at an angle giving a spiral appearance

Radial Cleavage

Perpendicular to embryos axis

Protostomes

Mouth forms first

Deuterostomes

anus forms first

Platyhelminthes Body Plant

• Dorsal Ventrally Flattened

• Acoelomates

• Blind Gut w opening on the “belly” - single opening for mouth and anus

• Cephalization

• Simple Nervous system w centralized ganglion(brain) w eyespots

• Hermaphrodites w complex reproductive system have a layered ovary/testes system w a genitcal pore

• Protonephridia for excretion- have pores

Platyhelminthes: Turbellaria = Free Living

• No circulatory system or structures for gas exchange constrains their size and shape

• Wholly or partially ciliated w gland cells for locomotion

• Chemoreceptors in Auricles (ear-like, triangular lateral projections located on the sides of a planarian flatworm's head)

• Can exchange sperm/eggs at same time in fencing copulation, have few offspring from fert eggs laid in masses and brooded

Platyhelminthes: Trematoday “Flukes”

• Have suckers for attachement and lack cilia

• Tegument or body covering used for protection and exchange

• Copulate by aligning genitals openings, have lots of offsprings w 1+ Larva stages. Find hosts thru chemical or tactile cues

Platyhelminthes: Cestodes (tapeworms)

• Head region called scolex for attachment w hooks, and the rest of the body parts called proglottids, used for reproduction

• Lack a digestive tract & protonephridia (excretion). Have gland cells secreting slime for locomotion and feeding

• Symbyotic/commensal/parasitic locating food w chemo receptors - carnivores

• Mesochyme membranes for support

• Cross or Self Fertilization- w lots of embryos that move posterior as proglottids (segments) move. Usually excreted in feces and have 2-3 hosts

Phylum: Nemertea “ribbon worms”

• Triploblastic with bilateral symmetry - UNSEGMENTED

• Spiral Cleavage - Protostomes - dorsollay flattened

• Have a ladder like nervous system with cerebral ganglion

• Closed circulatory system with hemoglobin that works with contraction of body against rhyncocoel (no direction)

• Complete gut w protonephridia equipped w flame cells close to blood suggesting excratory function

• Have defining Proboscis with Rhyncocoel

• Separate sexes with the ability to fragment

Nemertea Body Plan

• Complete Gut w Anus and Mouth, with proboscis used for food capture (long branched tongue-ish) paired with Rhynchocoel cavity thats not a true coelom

• Nerve Chords w Cerebral Ganglion

Proboscis

• Nemerteas defining feature - branched tongue type thing

• Works w tubes, muscles and hydraulics - muscles increase pressure in rhynchocoel - ejecting proboscis out which is then brought back in w retractor muscles and pressure relaxation

Nemertea Reproduction

• Gonochoristic (separate sexes)

• Find mates Through Chemoreception, external fertilization with some using hooks to attach while spawning

Phylum Mollusca:

• Bilateral Symmetry - Unsegmented - Triploblastic -

• Protostomes with spiral cleavage

• Have Coelom, full circulatory with hearts and complete guts

• Defining features being: Mantle, Foot and Radula

Mollusca’s Mantle

• Forms the body wall, forming groove or chamber called a cavity

• Houses the ctenidia for gills and gas exchange; water passes into the groove by cillary or muscle actio

• Receives: gametes, excretory products from nephridia and fecal discharge from anus

Mollusca’s Foot

• Used in digging, locomotion and attachement w muscles

• Its Cilliated w numerous gland cells

Radula

• Ribbon like tongue covered in chitnonous teeth used for scraping, predation and browsing in Molluscas

• Highly modified in some groups important in taxonomy

Mollusca Digestion

• Complete Gut, mucus carries it to the esophagus, which lead to a gizzard to grind up material.

• There can be structure called Crystalline style that rotates mucus string w food to release enzymes withtin the stomach

• Intestine gets food further digested extra and intercellularly

Mollusca Circulation & Gas Exchange

• Pump w vessels but open into a Hemocoel “open heart” where all the body tissue get bathed in hemocoel carrying oxygen.

• Use 2 Auricles in pericardial chamber to Pump Hemolymph “blood” that picks up digested product and oxygen at ctenidia

Mollusca Excretion & Osmo regulation

• Nephridia w Nephridiopore (the external opening (pore) of a nephridium) connecting to circulatory system to pick up byproducts from pericardial fluids

• Goes out through nephrostome into mantle cavity

• Pressure filtration, active secretion, and active absorption

Mollusca Nervous System

• Circumcentric arrangement of anglia in the head - innervate tentacles, statocysts, eyes buccal and head

• Paired nerve chords called pedal nerve chords and visceral nerve chords

• Pedal ones innervate muscles of foot & visceral ones innervate the mantle and viscera

Mollusca Sense Organs

• Eyes, Sensory Tentacled (simple pigments cups to cornea and lenses)

• Statocysts for balance and Osphradia - chemical sensors

Mollusca Reproduction

• Gonochoristic, sequential or simultaneous hemaphrodites

• Some groups reproduce via spawning eggs & sperm into water column where fertilization & larvae development take place

• Some can reproduce w specialized copulatory structures or have internal fertilization and release of eggs in masses

Class: Polyplacophora - Phylum: Mollusca

• Chitons - elongate molluscs w broad flat foot with 8 dorsal plates. Thick Mantle that covers a portion/all of the clates (aka girdle)

• Separate sexes w external fertlization

Chiton: Polyplacophora - Mollusca Body plan

Class Bivalvia ( mussels etc)

• Suspension Feeders with 2 hinged valves attached by ligament

• No head region, tentacles or radula w benthic adult stage

• Have abductor muscle that pull valve shut - when not active valves gape bc ligaments arent compressed

• Have a large mantle cavity and labial palps

Bivalves Shells/Valves

• Anterior and posterios siphons. Dorsal Top (where umbo is) & Ventral (where it gapes open)

• Umbo = tip pf the shell thats pointy and in a hump (back part where they join)

• Hinge & Hinge Teeth

• Pallial Line where Mantle attaches and aragonite & calcite shells

Bivalve feeding

• Using ctenidia (feather-like gills) to trap food material brought into mantle cavity, gill size and folding degree affect trapping

• Use Mucus & Cilia to trap and move material, some is ejected as pseudofeces by palps or redirected into mouth area

Bivalve Movement

• Infauna: dig using mechanical & Hydraulic pressure (razor clams) engorging foot w hemolymph, burrowing foot into sediment & acts as an anchor. Abductor muscles pull shell together & pedal retractor muscles pull shell downward

• Wedge shaped, hydrostatic skeleton & fill w fluid w bivalves

• Siphons extending to surface for gas exchange and food capture

• Or they cement themselves and attach to substrate at some point

Class: Gastropoda - Phylum Mollusca

• Asymmetrical molluscs with single, spiraled shell where body can be withdrawn. Undergo Torsion,

• Muscular creeping foot w an operculum

• Cephalized (head region) commonly w eyes & 1-2 pairs of eyes w snout

• Radula and some cristalline style

• Mantle Cavity housing ctenidia - osphradia

• 1-2 nephridia

• Include Sea Slugs, Bubble Snails and Sacoglossans

Torsion - Gastropoda : Mollusca

• Rotation of Visceral Mass up to 180 degrees in counter-clockwise direction (synamorphic 2 or more groups)

• Mantle cavity and anus moved over the head, organs on right r now are left. (torted or detorted) resulting in assymetry

• Loss of some right side organs and enlargement of left

• Occurs during development of veliger

Limbets or Abolones

• Detorted - retaining ancestral body plan

• Have holes and slits for water where water moves from heand and exits thru slits in abolones and volcano limpets

Typical Snails

• Water enters side of mantle cavity in this organism and go across ctenidia OR snail is torted 180

• Have Anus, Ctendium and Ospradium in mantle cavity

• W Operculum and shell

Operculum

What allows typical snails (gastropoda:Mollusca) to tuck into shell and “seal” themselves in

Nudibranchs - Gastropoda :Mollusca

• “Naked gills”

• Lost shell & torsion oin metamorphosis

• Some are Klepto-plastids (chloroplast) or -cnidae (nematocyst)

• Rely on chemosensory w osphradium to find prey

Sea Hares- Gastropoda: Mollusca

Have a reduced shell, can squirt ink. Can swim and crawl herbivore.

Cephalopoda: Mollusca

• Chambered Shell or highly reduced with complex eyes & tentacles around their heads & modified arms for copulating (differ in arms numbers)

• Have Radula with a beak ( can be paired w glands w paralizing toxins)

• Have 1-2 ctenidia

• Large ventral mantle cavity (predatory lifestyle)

• Muscular siphon used in jet propulsion (pl)

• Complex nervous system

• Can be chromatophores

Class: Polychaeta - Phylum: Annelida

• Segmented Worms “Anellus”

• Focusing on Class Polychaeta=Marine

• Tribloastic - Coelomates - Complete gut

• Closed circulatory system & Developed Nervous system

• Nephridia for excratory system also have trocophore larvae

Annelids Outer Body Parts

• Head region broken into 2 parts: Prostonium (segment before mouth to sense things and wedge in woild) & Peristomium (surrounding mouth) which is followed by more segmented regions

• End of Body have a second unsegmented region called the pygidum with anus and anal cirral

Polychaeta - Annelids

• Head Region, mouth, brain and pharynx can be highly specialized

• Externally covered in a cuticle & have bristles called setae or chatea

• Circular muscles to stretch and longitudal muscles to constrict (hydrostatic skeleton)

• Large coelomic space in each segment & suspended intestine thru whole body

• Dorsal & vetntral blood vessels w ring vessels

• Have ventral nerve chord

• Can be highly specialized suspension feeders or predators

• reproduce legit every which way

Chaetea

• Paired lateral outgrowths in polychaete, arranged along the body.

• Have 2 parts (biramous) called notopodium & neuropodium that each have the chaete in it

• Serve variety if function: locomotion, protection, gas exchange , water currents and anchorage

Polychaete : Annelids - Gas Exchange & Circulation

• Have blood w respiratory pigments

• Gas exhnage occurs throughout the whole body or highly localized— blood pumped ventrally to exhange area and then back

• Have pumps and valves

Excretion - Polychaetea: Annelids

• Use paired Nephridia - ducts

• Picks up fluids & reabsorbs material that isnt waste

• Urine different from cloelem fluid

Polychaetea: Annelids - Nervous System

• Have central Ganglion dicided into fore, mid and hind brain w different tasks

• Have segmented ganglion that innervate the body with pedal ganglion

• Have statocysts & are highly sensitive

Lophophorates

• Include Bryozoans & Brachiopods

• defined by the a structure called a lophophore- a cilliated tentacular feeding structure

• all have a u shaped gut & simple reproduction

• ALl secrete skeleton or casing

Phylum: Bryozoa

• Have Colonial zooids w separate sexes & can be hemaphrodites

• U-Shaped gut w Coelom & Lophophore

• Muscles to retract associated w body wall— have gelatinous/chitinous cuticle w calcified basal structure on some groups

• Mostly suspension feeders- use cilliated lophophore to move plankton to mouth

• Have water current chimneys

• No circulatory system use coelomic fluid exchange between zooids w gas exchange among surface and undigestiod amterial passed out a zoid

Bryozoa Body Plan

Colonies of zooids (can be polymorphic) produced by budding and housed in Zoecium. Each zoid has a lophophore & operculum, u gut, muscles and pores for gas exchange.

Can have a defensive avicularium

Have planktonic larva that have a gut

Repro