Marine Invertebrates Chapter 7 Marine Animals Without a

Marine Invertebrates Chapter 7: Marine Animals Without a Backbone

Background Information ● Kingdom Animalia ○ ○ ○ ○ ○ Phylum Porifera (Sponges) Phylum Cnidaria (Cnidarians) Phylum Ctenophora (Comb Jellies) Phylum Platyhelminthes (Flatworms) Phylum Nemertea (Ribbon worms) Phylum Nematoda (Nematodes) Phylum Chaetognatha (Arrow worms) Phylum Annelida (Segmented worms) Phylum Sipuncula (Peanut worms) ● Kingdom Animalia ○ ○ ○ ○ Phylum Mollusca (Molluscs) Phylum Arthropoda (Arthropods) Phylum Ectoprocta (Bryozoans) Phylum Phoronida (Phoronids) Phylum Brachiopoda (Lamp shells) Phylum Echinodermata (Echinoderms) Phylum Hemichordata (Hemichordates) Phylum Chordata (Chordates)

Background Information ● Invertebrate- An animal without a backbone or vertebrae ● About 97% of all species ● All phylum are represented in marine life, some are exclusively marine

Phylum Porifera (Sponges) ● ● ● No organs present, only aggregations of specialized cells Sessile- live attached to the bottom of the ocean Nearly all marine, ~8, 600 out of 15, 000 Simple body plans Full of ostia which allow water to flow through Plankton and organic matter is filtered through sponge for food

Sponges- Cells Pinacocytes- flat cells that cover the outer surface Porocytes- pore cells that water flows through Choanocytes- line the feeding chamber, have a flagellum and thin collar that traps food

Sponges ● Osculum- large opening at the top of the sponges where water leaves ● Sponges are filter feeders, a specific type of suspension feeder ○ Filter food particles out of the water ● Feeding: ○ ○ ○ Water enters in through the pores, ostia, is filtered by choanocytes Flows to the spongocoel, large opening in the center of sponge Water flows out of spongocoel, through the osculum, back into the ocean ● Sponges have spicules, either siliceous or calcareous for support ● Spongin- protein, skeleton of tough, elastic fiber ● Amebocytes- secrete spicules and spongin

Sponge Filter Feeding https: //www. shapeoflife. org/video/sponges-filter-feeding-made-visible

Sponges Asexual Reproduction: ● External Budding○ ● buds form on surface, fall to ocean floor when mature Internal Budding○ Sponge can die and leaves a bud internally that can grow back in the parents place Sexual Reproduction: ● ● ● Produce gametes in specialized collar cells Large, nutrient rich eggs and small sperm with flagellum Most sponges are hermaphrodites Sperm is normally released into the water, the eggs are internally fertilized when the sperm enter the sponge through the water Planktonic larva is carried by ocean currents until it settles on ocean floor and develops into a small sponge

Sponges 3 Classes: 1. Coralline Sponges- Calcium Carbonate spicules, siliceous spicules, and spongin, first known as fossils 2. Boring Sponges- Bore tiny channels through shells and corals 3. Glass Sponges- Siliceous spicules, leave behind their skeleton when they die

Phylum Cnidaria ● Sea Anemones, Sea jellies, Corals, Man of War, Hydra ● Radial Symmetry- parts of the body are arranged around a central axis ● Have an oral surface (mouth) and aboral surface (opposite side) ● Centrally located mouth, the only opening, surrounded by tentacles ● Mouth opens into the gut ● Prey is captured by nematocysts which sting prey which are found in cnidocytes in the tentacles.

Cnidarian Body Forms Polyp ● ● Sac-like stage Mouth and tentacles are pointed upward Sessile stage Ex: Sea anemone, coral, hydra (freshwater) Medusa ● ● Upside down polyp Motile, use jet propulsion ○ ● Relax to fill with water then contract to push water out of the bell Bell or umbrella shaped

Cnidarian Cellular Structure ● Body wall is made of two layers of cells: ○ Epidermis- external layer of cells ○ Gastrodermis- lines the gut ● Thin layer of mesoglea, gelatinous middle layer, no cells are contained. This layer is expanded to form the bell on medusas.

Cnidarian Classes 1. Hydrozoans: a. b. c. d. e. f. g. Wide range of form and life history Polyp and medusa stage present Medusa are normally planktonic, which release gametes into the water Eggs develop into free swimming larvae Larvae settle on the bottom, and develops into polyp Polyp reproduces and forms a colony Siphonophoresi. hydrozoans that make floating polyp colonies ii. Specialized polyps- floats filled with gas iii. Example: Portuguese Man of War, consists of multiple polyps that have specialized jobs

Cnidarian Classes 2. Scyphozoans: a. b. c. d. e. f. Larger sea jellies Large medusa are the dominant life stage Polyps are very small and release juvenile medusa Medusa bell can reach up to 3 m across Limited swimming ability, and can be carried by currents Horseshoe shaped gonads

Cnidarian Classes 3. Cubomedusae (Box jelly): a. b. c. d. Small, mostly transparent cube shaped medusa Minimum of four tentacles Ex: Sea wasps- one of the most dangerous marine animals https: //www. youtube. com/watch? v=Wr. MRwddl 7 i. Q

Cnidarian Classes 4. Anthozoans: a. b. c. d. e. Loss of Medusa stage Loss of cnidocil (stinging cells trigger function) Solitary or colonial polyps Make up majority of phylum, ~6, 000 species Gut has partitions (septa) which provide an increase in surface area for digestion f. Ex: Sea anemones

Cnidarian Classes 4. Anthozoans g. Corals: colonial polyps, most have calcium carbonate skeletons, occur in cold tropical waters h. Gorgonians (sea fans) secrete a branching skeleton of protein f. Black corals, secrete a hard black protein skeleton h. Soft corals, such as sea pens and sea pansies, do not secrete a hard outer covering.

Cnidarian Feeding ● Carnivorous ● Use nematocysts to capture ○ ○ Fluid filled capsule that contains a stinging thread that can be ejected, the thread can be sticky or have spines on it Some threads contain toxins ● After ingestion ○ ○ ○ Food enters gut, where extracellular digestion occurs Intracellular digestion occurs when the lining completes breakdown of food https: //www. shapeoflife. org/video/cnidaria ns-anemone-catches-goby

Cnidarian Behavior ● Specialized nerve cells- neurons ● Form a nerve net that transmits impulses throughout the cnidarian ● Some anemones can tell if there are genetically identical organisms around them with specialized nematocysts ● Some scyphozoans have primitive eyes, box jellies are one, than can form images ● Statocysts- small calcareous bodies that help with balance

Phylum Ctenophora (Comb Jellies) ● ● ● ● Exclusively marine, ~180 species Radially symmetrical Swim with 8 rows of ciliary combs, that beat in waves Common in warm and cold waters Carnivores, some are cannibalistic Two long tentacles with sticky cells- Colloblasts Normally appear multicolored due to light refracting on beating cilia

Ctenophora ● Examples: Comb jellies, sea walnuts, and sea gooseberries ● https: //www. youtube. com/watch? v=XSko_SUJDh. E

Phylum Platyhelminthes (flatworms) ● ● ● ● Bilateral body symmetry Dorsoventrally flattened (flat back and bellies) ~30, 000 species Simplest animals in which organs and organ systems are present Central Nervous System is present- simple brain and nerve cords Gut is similar to cnidarians, there’s only one opening Mesoderm (tissue between endoderm and ectoderm) is present- forms muscles, reproductive system, and other organs ● https: //www. youtube. com/watch? v=wn 3 xlu. IRh 1 Y

Platyhelminthes groups 1. Turbellariansa. b. c. d. Most common marine flatworm Free living carnivores Bright color patterns Live in symbiotic relationships with other marine organisms 2. Flukes a. b. c. d. Largest group of flatworms, ~18, 000 All are parasitic, feed on tissue, blood, or intestinal content Adult flukes always live in vertebrae Common in fishes, seabirds, and whales

Platyhelminthes Groups 3. Tapeworms (Cestodes): a. Parasitic flatworms b. Normally have a long body with repeated units c. Live inside intestine of most vertebrates d. Head of worm attaches with scolex (hooks, suckers, etc. ) e. Absorb nutrients from intestinal content f. Can get up to 40 m long

Phylum Nemertea (Ribbon worms) ● ● ● Look similar to long flatworms ~1, 300 species, mostly marine Found in shallow temperate waters Complete digestive tract- gut includes a mouth and an anus Body cavity and circulatory system are present Proboscis- long fleshy, tube used to entangle prey, everted from a cavity to feed ● Feed on worms and crustaceans ● Can get up to 30 m long

Phylum Nematoda (Roundworms) ● Rarely seen ● Many species are parasitic ● Small, with slender and cylindrical bodies that are pointed at both ends ● ~15, 000 -80, 000 species and up to half a million undiscovered ● Have a complete digestive tract, with a developed fluid filled body cavity ● Hydrostatic skeleton- layer of muscles in a tough, flexible body wall that pushes and squeezes against the fluid in the body cavity ● Can feed on bacteria, live inside seal and dolphin guts, or can be on the flesh of fish

Phylum Chaetognatha (Arrow Worms) ● ● ● ● One of the smallest animal phyla ~100 species, all marine Important member of the plankton Almost transparent, fish-like fin and tail Head: eyes, grasping spines and teeth Have efficient sensory structures for hunting Carnivorous, small crustaceans, eggs of fish, other arrow worms Swim in rapid darting movements

Phylum Annelida (Segmented worms) ● ~20, 000 species ● Body plan ○ ○ ○ Consists of a series of similar compartments (segments) The gut goes through all segments and lies in the coelom (cavity surrounded by tissue from mesoderm) Coelom is filled with fluid and divided according to the segments Coelom and segments act as a hydrostatic skeleton Have longitudinal and circular muscles Muscles allow for annelis to be efficient crawlers and burrowers

Annelida Classes ● Class Polychaeta: ○ ○ ○ ○ Each body segment has parapodia ■ Parapodia-flattened extensions with sharp bristles (setae) ~10, 000 species, almost exclusively marine Proboscis lined with jaws Closed circulatory system- blood is enclosed in blood vessels Excretory organs Gills are present in the parapodia Have a larval stage, trochophore, which has a band of cilia around the body ■ This larvae stage is present in other invertebrate species

Annelida Classes ● Polychaete Examples: ○ ○ ○ Glycera, blood worms feed on small prey Terebella ■ Tube polychaete, reduced parapodia, have tentacles covered with cilia and mucus ■ Suspension feeders Sabella, Feather duster worms ■ Feathery worms covered in cilia to trap, sort, and transport material Tomopteris ■ Planktonic stage of life cycle Eunice ■ Posterior end of body can break off to spawn, swarming https: //www. youtube. com/watch? v=c. GD 8 EJD 2 Vk. U

Annelida Classes ● Beard Worms/ Pogonophorans ○ ○ ○ Specialized Polychaetes Lack a mouth and gut Have a tuft of tentacles Tentacles help the worm absorb nutrients ~130 species, normally restricted to deep water ~20 species are found near hydrothermal vent and deep whale remains

Annelida Classes ● Class Hirudinea (Leeches) ○ ○ Mostly freshwater, but marine leeches occur Attach to fish and invertebrates Sucker at two ends No parapodia ● Class Echiura (Echiurans) ○ ○ ○ Look like soft, unsegmented sausage Live buried in sand or cal Non-retractable spoon-liked or forked proboscis ~230 species, all marine Deposit feeders

Phylum Sipuncula (Peanut worms) ● Soft unsegmented body ● Coelom is present ● Burrow in mud, rocks and corals or hide in empty shells ● ~150 species ● All are marine, mainly shallow water ● Deposit feeders ● Mouth with small lobes and branching tentacles