exam 3 Marine Science

phylogeny

tree of evolutionary descent of species

choanoflagellates

closet living relatives to animals

• individual choanoflagellates are very similar to choanocytes, sponge cells

protist

a eukaryotic organism that is not an animal, plant or fungus

protista

not a monophyletic group, but a taxa used for convenience

choanocytes

sponge cells

What two groups make up metazoa, how do they compare

Parazoa—sponges

• no distinct tissue types

• body cells have a high degree of independence

Eumetazoa—other animals

• body symmetry

• gut and nervous system

• tissues which are organized into organs

What is metazoa

animals

Poriferans general characteristics

sponges

• asymmetrical

• no true tissues (lack organs)

• benthonic-epifauna

• sessile

• found worldwide, abundant in temperate waters but diverse in tropics

The 3 sponge classes and what defines them

Calcareous—made of calcium carbonate

Demosponges and Hexactinellids —silicon dioxide

what are sponges made of

spicules

sponge anatomy and functions

chonaocytes—generates water currents to filter food, then engulfs bacteria/food particles by phagocytosis

mesohyl—gas exchange, support, and waste removal

amoebocytes—take up food, digest it, carry nutrients to other cells, manufacture spicules, and can become gametes

Asconoid

sponges shaped like a simple tube perforated by pores

has a single opening (the osculum)

syconoid

larger than asconoid

tubular body with a single osculum and clear spongeocoel cavity

has a thicker body wall, and the pores that penetrate it are longer, forming a system of simple canals

leuconoid

largest and most complex sponge

made of masses of tissue penetrated by numerous canals that lead to small chambers lined with collar cells, and lead out to a central canal and osculum

how do sponges reproduce?

asexually and sexually

sponge sexual reproduction

hermaphrodites—most sponges, produce eggs and sperm but they do not self-fertilize

water currents carry sperm between individuals

occurs in the mesohyl

produces free swimming larvae

sponge aseuxal reproduction

budding and fragmentation

factors driving sponge distribution

only live in areas where there is substrate they can attach to, and avoid areas with high exposure to wave energy, because sediment can clog pores

attracted to clear waters and currents

similar nutrient availability and temp ranges to coral

why are sponges in the tropics brightly colored?

symbionts

sponge nutrient loop

they facilitate the transport of organic matter

holobiont relationship

sponge hosts a diverse community of microbes i.e bacteria, fungi

how do sponges protect themselves, and from who

predators, competitors, parasites, and harmful bacteria

they produce secondary compounds

Azidothymidine

AZT, breakthorugh HIV drug produced from sponge chemicals

Two major ways sponges feed

filter feeding and carnivorous

Where is the death ball sponge found

southern ocean

how do warming temps and acidity affect bio-eroding sponges?

does not directly impact them, but it destabilizes their microbiome

similarity between ctenophores and cnidarians

diploblastic animals with a mesoglea

mesoglea

acts as a hydrostatic skeleton, supports body shape, buoyancy and movement

Cnidarians vs ctenophores: body structure, cels, and lifestyle

Cnidarians

• radial symmetry

• incomplete gut

  • mouth is connected to the gastrovascular cavity, a blind sac

    • digestion, circulation. gas exchange, and hydrostatic skeleton

• cnidocytes with stinging cells

  • tentacles capture and ingest food

  • cnidocytes have large stinging organelles called nematocysts which have toxins

• nektonic and benthonic

Ctenophores

• complete gut

• no stinging cells

  • instead use colloblasts—produce a sticky substance to trap prey

• 8 comb like plates for swimming—ctenes

• Nektonic

Cnidarians body plan

sessile polyp (aseuxal phase) and motile medusa (sexual stage)

some are dimorphic—exhibit both body plans during their life cycle

life cycle of dimorphic cnidarians

mature polyps produce medusas via asexual budding

medusas reproduce sexually and produced ciliated larvae called planulae

• the planulae settles to the bottom and develops into polyps

Hydrozoa

• have polyps and medusa

• medusas are called hydromedusas

  • have a muscular value below the margin of the bell

what is the most famous hydrozoan, and describe it how it functions and how it’s dispersed

Portuguese man o’ war

it is not an individual but a colony (siphonophore) made of individuals called zooids-clones,, female and male colonies

• pneumatophore—floating device that primarily consists of carbon monoxide

• gonozooids—reproduction

• gobodendra—released from colony when mature

• gastrozooids—digestion

• dactylozooids—catching prey

• coiled stinging tentacles that are up to 30m long

• traps food with menatocysts

Found in tropical and subtropical seas, dispersed by winds and ocean currents

Blue dragon sea slug

eats man o war’s, and repurposes their stinging cells for own defense by storming them in the cerata

Scyphozoa class

though it has a polyp stage, it’s most prominent stage is medusa

free swimming, solitary carnivores

separate sexes

gonads formed in the gastrodermis, and expelled through the mouth

Lion’s mane medusa

Scyphozoa class

appear in the Northern Atlantic between April and May

grow rapidly in the summer, becoming very large by august

• during this time they drift with wind and tides into aggregations with others and reproduce

male or female

eggs are storied in the oral tentacles of the female, where they are fertilized and develop into planulae larvae

What controls cnidarian behaviors

no brain or centralized nervous system

instead, they have a large nerve net controls swimming and a small nerve net controls all other behaviors

Rhopalia

sensory organs located in the medusa of Scyphozoa and Cubozoa

contains ocelli which are photoreceptors (sense light)

also contains statocysts—equilibrium, balance, sensory receptor

Cubozoa class

box-shaped medusa

50 species within tropical waters

15-25 cm

differ from Scyphozoans in arrangement of tentacles in muscular pads called pedalia

pedalium—one or more tentacles

separate sexes, fertilizations occurs within females

• planula larvae develop inside female or are released

• planula develop into a polyp, which bud into more polyps to create a colony

• polyps transform into medusas

rophalium—houses eyes that have a lens, retina, iris and cornea

most dangerous jellyfish—box jellyfish aka sea wasp

• toxin affects heart, nervous system and skin cells

Mollusks body sections

Foot—a muscular structure originally used for locomotion and support for internal organs

Visceral mass—heart, digestive, excretory, and reproductive organs

Mantle—fold of tissue covering the visceral mass, it secretes the calcareous shell

• mantle cavity—where the mantle extends beyond the visceral mass, within it is gills for gas exchange and filter feeding

defining feature of mollusks

calcareous shell

radula

protruding, rasping, lounge-like organ with rows of tiny teeth used to eat algae

in some species it can deliver a lethal sting to neuroreceptors to capture prey

• venom is conotoxin

in some snails it is used as a drill or poison dart

reduced in cephalopods

• instead, they have a beak which is connected to a venom producing gland

mollusk head region

well-developed, contains simple to complex eyes, tactile organs, chemoreceptors

eyes vary from simply containing photoreceptors to a complex eye with a lens and cornea

do all mollusks have a shell?

no, nudibranchs and sea slugs of Cephalopods have lost thier shell

Are cephalopods nektonic?

yeth

evolution of the shell in cephalopods

lost in octopuses, internalized in squids and cuttlefish

shell shifted from defense to a flotation device

cephalopods general characteristics

cephalopod sexual reproduction

once in a lifetime event

male uses specialized arms called hectocotlyus to transfer spermatophores or or in the family

• however, not found in Nautilus

• instead, they engage face to face with females for 24-30 hours

in octopuses, females guard the eggs, but squid and cuttlefish do not

where are Nautiluses found

found in South Pacific waters of Indonesia and the Indian Ocean

Nautilus anatomy

only shelled member of mollusks

shell divided into chambers which are penetrated by tubes through which gases and liquids are moved to control the animals buoyancy

tentacles do not have suckers

two longer tentacles for olfaction

radula

where are squids found

North Atlantic, Southern Oceans, Eastern Pacific

squid anatomy

Humboldt squid speical ability

has thousands of photophores throughout its body, which highlight the color-changing chromatophores in the skin

where are cuttlefish found..not found?

found in tropical and temperate ocean waters

• shallow costal areas, reefs, and seagrass beds in the eastern Atlantic, Mediterranean, Africa, and Asia

not in the Americas!

cuttlefish anatomy

8 arms with suckers

2 tentacles with suckers at the end

internal shell—cuttlebone is made of aragonite (carbonate)

camouflaging organs in Cephalopods

Chromatophores

neuromuscular organs that allow them to change color instantly

• contains a structure with pigment that is attached to muscles, each with its nerves and glia

• when excited the muscles contract, expanding the chromatophore

pigments associated are black, red and yellow

Iridophores—iridescent greens. blues, silvers and golds

leucophores

where are octopuses found

worldwide

octopus anatomy

in addition,

they have 3 hearts

and thier blood contains copper-rich protein, hemocyanin

what poison is associated with the Blue Ringed Octopus

Tetrodotoxin, no anti-venom

do male octopuses die after mating

immediately or up to a few months after

Cephalopod sense organs

good eyesight though colorblind

either have U0shaped, W0shaped or dumbbell shaped pupils which allows light to enter through lens from many directions

excellent sense of touch, their suction cups are equipped with chemoreceptors to taste what it is touching