Marine Invertebrates Flashcards
What are the four classes of Porifera?
Demospongiae, Calcarea, Hexactinellida, and Homoscleromorpha.
What kind of marine invertebrates do the phylum Porifera refer to?
Sponges.
Phylum Porifera is also known as what? Why?
Pore-bearer. This is due to the significance of pores for sponges as pores are the major characteristic of sponges and help them function entirely.
What are the key characteristics of Porifera?
No nerves, muscles, or complex organs, though they have specialized cells. All aquatic, some marine. Sessile.
What is the main goal/function of Porifera bodies?
To maximise water flow, allowing oxygen, nutrients, etc.
What are Ostia?
Ostia are narrow pores on Porifera bodies that direct water flow into the body.
What are Oscula?
Oscula are wide pores that expel the water in the body that’s brought in by the Ostia and filtered by choanocytes/choanocyte chambers.
Porifera have specialized, totipotent cells, what does this mean?
Totipotent cells refer to cells that are able to develop into a cell of any function. Porifera contain choanocytes and amoebocytes.
How do Porifera sexually reproduce?
Sexual reproduction for Porifera is typically hermaphoroditic, and involves their totipotent cells becoming sperm (choanocytes) and oocytes (choanocytes and amoebocytes). They’re fertilized either externally or in the mesophyl and result in larvae.
How do Porifera asexually reproduce?
They can asexually reproduce via fragmentation, where pieces of them may break off and form an individual organism, or gemmules. Gemmules are a tough-coated dormant cluster of embryonic cells that can be produced in fresh-water sponges. These can be produced in the event of unfavourable conditions and can result in the generation of a new sponge.
What makes sponges such efficient sessile filter feeders?
Their body plans maximize water flow which provides oxygen and food, different body plans work differently and focus on surface area as well.
What are the different body plans of Porifera?
Asconoid, syconoid, and leuconoid.
What defines an asconoid body plan of Porifera?
The asconoid body plan are the simplest of the Porifera body plans and involve choanocytes lining the spongocoel (large middle cavity). Tend to be very small Due to their surface area/ratio. *Refer to Lecture 2 - slide 11 for images.
What defines a syconoid body plan of Porifera?
Choanocytes line the side chambers (radial chambers) rather than the large middle cavity (spongocoel).
What defines the leuconoid body plan of Porifera?
Choanocytes line small choanocytes chambers across the sponge, though there’s no spongocoel. Most sponges have this body plan. These can grow extremely large Due to their surface area/ratio.
What are spicules?
Spicules are the structural support for sponges. They can either be calcareous (made of calcium, do diseintegrate in hcl) or silliceous (made of silica, do not disintegrate in hcl). They’re also a form of defence for sponges with their fibreglass-like feeling.
Do bath sponges have spicules?
Bath sponges do not have spicules, which is what gives them their soft and squishy feeling. They instead have collagen spongin which still provide structural support such as spicules.
Porifera are filter feeders, what does this mean?
Sponges are size selective particle feeders, they obtain food by taking in water that contains the nutrients and filtering them, as well as oygen, out of the water via choanocytes. The water continues to be pushed out of the osculum and the nutrients are passed to the amebocytes which transport them to other cells.
What Porifera are not filter feeders?
Carnivorous sponges. They lack a filtering system entirely and instead entangle their prey with spicule-covered filaments that are then digested via amebocytes.
What defines the Porifera class Hexactinellida?
They’re marine, mostly deep sea species that have strictly silliceous spicules with six rays. They either have a syconoid or leuconoid body plan and contain little mesohyl (collagen/galectin/more that fills space between sponge layers, much like an endoskeleton).
What defines the Porifera class Calcarea?
Marine and shallow water sponges that have calcareous spicules with 3-4 rays. They can be any body plan.
What defines the Porifera class Demospongiae?
The most common class among Porifera, with around 83% of sponge species being Demospongiae. They can be Marine or freshwater, can be carnivorous, and are all leuconoid. They can have siliceous spicules, spongin, or both.
What defines the phylum Porifera?
9,212 species. Multicellular sieves. No organs, lack of true tissues. All aquatic and sessile, most marine, 4 classes.
What defines the phylum Cnidaria?
11,861 species - mostly marine, 23 are freshwater. Two tissue layers, 6 classes. No organs or circulatory system. Radial symmetry, colonial, nematocysts. Body plan of sac and tentacles.
What are the main marine Invertebrates of Cnidaria?
Jellyfish, sea anenomes, corals, etc. Soft bodied stinging animals.
What are the two body plans of Cnidiria?
Polyp and Medusae. Polyp is commonly found on the bottom of bodies of water (benthic), are sessile and tube like with a thin mesoglea and hard skeletons (sea anenome). Medusae are free-swimming and bell shaped with thick mesoglea and no skeleton (jellyfish).
What is the locomotion of a Cnidaria with a polyp body plan?
They can move via ‘muscle’ contraction - hydrostatic skeleton. They can also craw across surfaces via the pedal disk on the bottom of their ‘foot’.
What is the locomotion for a Cnidaria that has a Medusae body plan?
They rely on mesoglea and sea water to swim. They contract their “muscles” to force water behing them, pushing themselves forward.
What are the three relevant classes of Cnidaria?
Anthozoa, Scyphozoa, and Hydrozoa.
What defines the Cnidarian class Hydrozoa?
They have both a polyp and medusa stage, where their polyps are usually colonial and are formed by budding. They’re usually polymorphic and each have different functions (gastrozooid for feeding, gonozooid for reproduction, dactylozooid for defense, and stolon for structure).
What’s the Cnidarian class Hydrozoans life cycle?
Fertilized egg - larva - polyp colony - asexual budding via gonozooid - hydromedusa - sexual reproduction.
What are the key characteristics of the Cnidarian class Anthozoa?
All marine, don’t have medusae in their lifecycle, only polyps. Can be solitary or colonial. Can have hard corals (scleractinia - mostly colonial), anemones (actinaria - solitary), sea fans and sea whips (alcyonacea), or sea pens and sea pansies (pennatulacea).
What are scleractinians, what are their key features?
Scleractinians are an order of Anthozoa that consist of anemones. They’re polyps connected by a thin tissue and involve a wide range of polyp integration. Polymorphism is pretty much absent.
What’s the key difference between Hexacorallia polyps and Octocorallia polyps?
Hexacorallia polyps are simple tentacles in multiples of six, while octocorallia are feathery tentacles, that are always in eight.
What’s special about Anthozoan reproduction?
They lack a medusa stage. They can be hermaphroditic or dioecious and can reproduce via free-spawning or brooding. Asexual reproduction involves fission, budding, and fragmentation.
What are the key features of the Cnidarian class Scyphozoa?
Scyphozoa are true jellyfish, there are only around 200 species and lack (or have a reduced) polyp stage. Their gonads are found inside their gastrovascular cavity (with gastric filaments), have no vellum, have 4 oral lodes and highly branched radial canals.
Cnidarians are carnivores, how do they catch their prey?
Via their tentacles and stinging cells which contain nematocysts.
What kind of organism does the phylum Platyhelminthe refer to?
Flatworms.
What are some of the key features of Platyhelminthes?
Three tissue layers (ecto, Endo, meso), true organs, acoelomate, cephalized with a simple nervous system, bilateral symmetry, incomplete gut, lacks a circulatory system and relies on diffusion (which results in flat body).
What are some of the features of the Platyhelminthe circulatory system?
Platyhelminthes lack a circulatory system, therefore they rely on diffusion for gas exchange and circulation (increased SA/V = increased diffusion for larger organisms).
What are some of the features of the Platyhelminthe excretory system?
They have protonephridia, a excretory system that acts as a canal system which ends in flame bulbs and nephridopores. Flame bulbs are specialized excretory cells, and nephridopores refer to the opening for waste to exit the body.
What is a coelom?
A coelom is the main fluid-filled cavity in the body of an organism. It’s located between the intestinal cavity and the body wall. It acts as protective cushion for organs.
What kind of coelom do the phylum Plythyhelminthes have?
Acoelomate, they have no coelom. Instead the cavity/blastocoel is completely filled with mesoderm.
What are the three relevant classes of Platyhelminthes?
Turbellaria, trematoda, and certoda (flatworms).
What are the key features of the Platyhelminthe class Turbellaria?
Free-living, ciliated epidermis that allows for locomotion, variable intestine shape, carnivores, and ability to reproduce sexually and asexually.
What are the key features of the Platyhelminthe class Trematoda?
Parasitic - larvae on Invertebrates, adults on vertebrates, highly host specific with the ability to influence host behaviour. Eggs hatch inside invertebrate guts - sporocysts live in Invertebrates till digested by vertebrates where they grow in gut.
What are the key features of the Platyhelminthe class Celtoda?
Tapeworms, parasitic, larvae affect invertebrates, adults affect vertebrates, no mouth - only feeds via diffusion - therefore must be inside an organism. Body is mainly proglottids - segments that contain male and female reproductive organs.
What are the benefits of a coelom?
It separates the body wall from the gut, allows for transportation, extra organ space, and hydrostatic skeleton.
What organism defines the phylum Annelida?
Ringed/segmented worms.
What are the key features of the phylum Annelida?
Coelomate (have coelom form in the mesoderm), segmented, muscular, closed circulatory system, complete digestive tract with regional specialization, well developed cephalized nervous system.
What is tebolastic growth?
When segments develop in the zone between the head and the tail rather than from one end.
Continuous structures vs. repeated structures.
Continuous structures continue across different segments, while repeated structures repeat within segments, not continuing across them.
What is tagmantization?
Tagmantization is a division of an organism body into specialized compartments.
How do Annelids undergo gas exchange and digestion?
Gas exchanged via skin/high surface area structures, and digestion via specialized gut regions, where only some regions absorb food.
How do Annelids excrete?
Via the excretory organ metanephridia. Removes waste from the coelom (coelomic fluid) with nerphrostome (funnel-like compartment that lets waste pass into the excretory system).
What are the key features of the Annelida class Clitella?
Have clitellum (pronounced glandular region of epidermis used for reproduction), hermaphrodites with permanent gonads.
What is the defining organism of the Clitella subclass Oligochaetes? What are their key features?
Earthworms, they make up majority (85%) of Clitella. Keay features include lacking parapodia and having few setae, few sensory structures and are key decomposers.
What are the defining organisms in the Clitella subclass Hirudinea? What are their key features?
Leeches, they evolved from Oligochaetes and are especially flattened with two suckers, no setae, and are predator/parasites, must stretch and shrink across the whole body due to incomplete septa.
What does a compartmentalized coelom allow for?
Locomotion via hydrostatic skeleton - the fluid filled compartment can change shape, though the segment volume is constant.
What is peristalsis?
Peristalsis is waves of muscular contraction, circular muscles contracting = the segments stretch, and longitudinal muscles contracting = the segments shrink.
What are the key factors of the Annelid class Polychatea?
Mostly marine, have parapodia (paddle-like appendages) with setae/chaetae, well developed nervous system, doecious with no permanent gonads, and can be mobile or sedentary.
What are the key features of mobile Polychaeta?
Predators, can be benthic or planktonic, well developed parapodia and sensory structures, raptorial head structure and similar segments.
What are the key features of sedentary Polychaeta?
Burrow/tube dwellers, have reduced parapodia, modified body regions with ciliated tentacle crown and ‘hook-like’ septae to hold onto tube, feed via deposit/suspension feeding (feed via capture of particles).
How do the Annelid class Polychaeta reproduce?
Via epikotes in errant polychaetes - epikotes (gamete carrying cells specialized for swimming - baby worms -atokes are adults) are produced by epigamy (worm transforms into reproductive morph) schizogamy (asexual reproduction - fission).
What are the key features of Mollusca?
8 Classes, second most diverse phylum with highly diverse habitat and form. Have a four part body plan (head, foot, mantle, and viceral mass). Bilateral symmetry, open circulatory and have metanephridia.
How are Mollusca shells made, and what are they made out of?
They’re secreted via the mantle, they’re made from calcium carbonate, and contain three shell layers - nacreous layer (makes paua shiny, the prismatic layer (minerals), and the peripitracum (outer layer).
What are the pros and cons of shells for molluscs?
They provide protection from predators as well as desication, and they provide structure and rigidity, however, they also prevent and limit growth and movement. They also lower the overall surface area per volume of the organism.
What is the foot used for in Mollusca?
The foot in Mollusca allows for movement via the muscles (walking and digging), some organisms are also able to use this foot to swim.
What is the mantle cavity in Mollusca?
The mantle cavity is a space that’s formed via the folded body wall on the dorsal side of the body, this is usually covered by the shell and has ctenidia, openings to the gut, gonads, and kidneys.
What are ctenidia in Mollusca? How do they help with gas exchange?
Ctenidia in Mollusca are gills, they function in gas exchange via a central shaft with feathery filaments - lamallae. They push oxygen through the organism.
How does circulation typically occur in molluscs?
They have an open circulatory system with a chambered heart. They can have red blood or blue blood. Blood is pumped into the hemocoel where it gets deoxygenated in Ctinidia before going back to the heart.
What are racula in Mollusca?
Long ribbon/belt like toothed feeding structure, scrapes algae off of surfaces and prevents algae from overpopulating areas. Teeth eventually dull and wear down, however there’s continuous tooth regrowth.
What are the relevant classes of Mollusca?
Polpacophra, Gastropoda, Bivalvia, and Cephalopoda.
What are the key defining features of the Mollusca class Polpacophra?
All marine species, shell made of 8 overlapping plates/valves, which allows for more movement and space (e.g. like chiton), girdle (can be many different textures) covers the plate edges, dioecious with simple nervous system and “shell eyes”.
What are the key defining features of the Mollusca class Gastropods?
Largest class, very diverse. Body is twisted in relation to the foot (torsion). They can be dioecious or hermaphroditic, and have sensory organs on the tentacles and foot.
What are the two different kinds of Gastropoda? How do they differ?
Basal Gastropods and Intermediate Gastropods. Basal Gastropods include paua and Intermediate Gastropods include snails.
What are the negative effects of torsion in Gastropoda? How do Basal and Intermediate Gastropods solve this?
Torison results in the anus, nephridipore, and Ctinidia surrounding the head - unsanitary. To prevent/solve this, Basal Gastropods have holes in their shell that allows for water flow to pass through, taking away waste. Intermediate Gastropods rearrange themselves so that the Ctinidia is on the left of their body, and the anus and nephridiopore is on the right side of their body. Water flow still removes waste.
What’s an operculum?
An operculum is an Intermediate Gastropod structure that allows for the organism to completely close it’s shell (acts somewhat like a shell trapdoor).
What is the benefit of conispiral shells versus pranispiral shells?
Conispiral shells are asymetrical, which allows for more balance and support, however, they’e more compact and have reduced organ space in some parts of their body, resulting in a lack of organs in those areas.
What are the key defining features of the Mollusca class Bivalves?
Bivalves have a hinged shell, no head or radula, are sessile filter feeders, have siphons (tubes to pass water through body), and sensory structures on the edge of the mantle. Some can swim using the coin shaped muscles used to close the shell.
If Bivalves have no head or radula, how do they feed?
They’re filter feeders, and feed via modified ctenidia that can help capture food.
What are the key defining characteristics of the Mollusca class Cephalopoda?
Include squid, octopus, etc. Active swimmers, closed circulatory system, well developed nervous system, and some have internal shells.
How do Cephalopoda swim?
By using their siphuncle which is filled with gas, when that gas escapes fromt the bottom, it allows jet-like swimming.
What’s unique about Cephalopoda ctenidia?
Their Ctinidia is not ciliated, instead they use their muscles to cover their gills in water.
What are the defining organism of the Phylum Arthropoda?
Crustaceans.
What are the key defining characteristics of the phylum Arthropoda?
The largest phylum with 1 million species. They’re mostly aquatic and contain 10 classes. Rigid exoskeleton, jointed appendages, segmented, tagmata, open circulatory system, no cilia.
What functions do exoskeletons on Arthropods provide?
Protection from desication, predators, parasites, etc, and site of muscle attachment.
What is the function of the cuticle on the exoskeleton of Arthropods?
It’s the hard, external layer of the Arthropods body. It provides protection, support, defense, and helps with sensory and locomotion.
What is the cuticle of an Arthropod composed of? How is it made?
Made of mainly chitin, it also contains polysaccharide. It’s secreted in the epidermis and hardens via mineralization (with minerals e.g. calcium carbonate).
What are the processes molting and ecdysis in Arthropods? How do they occur?
Molting is the act of growing new cuticle after the old one has been shed (ecdysis). The epidermis detaches and a new one is secreted, the old cuticle splits, allowing the new cuticle to expand and tissues to grow.
What are hox genes in Arthropods?
They’re a group of genes that regulate body structure development. Arthropods show these in their tagmata - by activating the Ubx gene in the head, a new leg develops.
How do hox genes in Arthropods relate to their tagmata? Benefits?
Their specialized segments are under the developmental control of different hox genes, making them independent. Released from developmental constraints, more room to modify body plan, more possible directions for evolution.
What are the key features of the Arthropod subphylum Crustacea?
They have 2 pairs of antennae, diverse sensory organs and eyes, osmoregulatory and excretory organs, and a carapace (outgrowth from the back of the head).
How do Crustacea reproduce?
Dioecious (except for barnacles), internal fertilization, sticky eggs and external brooding - direct development or various larval stages.
What defines Crustacea appendages?
Biracious - forked, 5 pairs of head appendages, 8 pairs of thoracic appendages, and 6 pairs of abdominal appendages.
What are Crustacea appendages used for?
Antennae are for sensory, maxillae are mouthparts, maxillipeds are for feeding, pereiopods are for walking, pleopods are for swimming, and uropod is a tail.
What are the three relevant classes of Arthropods/Crustacea?
Cirripedia, Copepoda, and Malacostraca.
What are the key features of the Crustacea class Malacostraca?
Majority of Crustacea (75%), 5/8/6 appendage (head/thoracic/abdomen), 10 orders.
What are the key features of the Crustacea class Malacostraca order Decapoda?
Highly diverse order with 10 legs, have very complex behaviour. Includes shrimp, crabs, and lobsters.
What defines Decapod (Malacostraca class - Arthrodpod phylum) appendages?
Gills are located on the side branch of thoracic legs (peripopods - walking legs). The first/second pair of peripopods may be chelipeds (Chela tips, aka clawed). Abdominal legs (pleopods - for swimming) can be modified for reproduction.
What defines the body plan of the Malacostraca class, Crustacea phylum Decapod? Shrimps vs. lobsters and crayfish.
Shrimp are laterally compressed (squished side to side), they have a well-developed abdomen and pleopods and are capable of walking. Lobsters and crayfish however are more flat than compressed, sometimes have claws and have a well-developed tail fan (uropod) and walking legs.
Describe the body plan of Decapod body plans (true crabs).
Have reduced abdomen and pleopods, a well-developed carapace, and most have asymmetric claws. Hermit crabs are adapted to live in shells with a soft abdomen, reduced appendages, tail fan modified for gripping shells, change shells after molting.
What defines the Melocostraca order Euphausiacea?
Krill, gills outside of the carapace, no maxillipeds, thoracic appendages form a feeding basket, highly abundant in cold water.
What defines the Melocostraca order Amphipoda?
Sand fleas, laterally compressed with no carapace.
What defines the Melocostraca order Isopoda?
Pill bugs, no carapace, flattened, and benthic/terrestrial.
What defines the Crustacea class Copepoda?
Many are parasitic to fish, have no carapace, a short thorax, no abdominal appendages and have 2 antennae used to prevent sinking and to swim. Many filter feed and others are predators.
What defines the Crustacea subclass Cirripedia?
‘Hairy foot’, example: barnacles, three types: acrons, goose-neck, and parasites. Sessile, glued to hard substrates, suppressed abdomen, thoracic appendages are highly modified for filter feeding and respiration.
What are deutrostomes and protostomes, what’s the difference between them?
Protostomes are more basal species where the first opening in the embryo becomes the mouth, while in deutrostomes, the first opening becomes the anus.
What are the key features of the phylum Echinodermata?
Bilateral larvae with pentaradial adults, no head/all head, no osmoregulatory structures, large 3-part coelom with all parts being used for circulation, regeneratve abilities, simple gonads, dioecious and free spawning, lack a respiratory system but have a complete digestive system (sometimes no anus).
What are the three parts of the three part coelom in Echindothermata?
Perivisceral coelom, water vascular system, and the hemal system.
What does the water vascular system in the Echinodermata coelom do? What’s a madreporite?
It manages circulation, gas exchange, excretion, and locomotion. It’s a closed system of canals and tube feet. Madreporite - opening that filters water into the system.
What’s the spiny skin of Echinoderms made of?
Endoskeleton formed from ossicles (CaCO3). Can fuse into skeletal plates and is formed in the dermis covered by epidermis and bound by tissue and muscle.
What is a pedicellariae in Echinoderms?
Pincer like structures produced by ossicles.
What are the four relevant classes of the phylum Echinoderm?
Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea.
What are the key features of the Echinodermata class Asteroidea?
Sea starts, flattened with central disc, carnivorous, aboral anus, suckered tube feet, two chambered evertable stomach with gonads in each arm. Gas exchange via tube feet and papulae.
What are the key features of the Echinodermata class Ophiuroidea?
Brittle stars, scavengers, complex skeleton, reduced water vascular systems, tube feet without suckers and ampullae, no pedicellariae. Sac like unevertable stomach - has jaw.
What are the key features of the Echinodermata class Echinoidea?
Kinda, grazers, ossicles fused into test (shell). Abundant spines and pedicellariae. Simple gut, gonads and water vascular system in the test/shell. + Aristotles lantern = complex jaw.
What are the key features of the Echinodermata class Holothuridae?
Sea cucumbers, walk/burrow, worm like, suspension feeders, tube feet are on the ventral side or absent with suckers, feed with buccal tentacles (modified tube feet). Thick body wall, muscular with microscopic ossicles. Respiratory tress and evisceration (discharge internal organs).
What are the key characteristics of the phylum Chordata?
Coelomate deuterostomes, complete gut, dorsal hollow nerve cord with post-anal tail.
What are the key characteristics of the Chordata subphylum Urochordata?
Marine species with notochord and nerve cord in larvae, filter feeding in adult, tunic (outer body wall) made of protein, cellulose and water. living exoskeleton.
What are the key characteristics of the Urochordata class Ascidiacea?
Sea squirts, benthic filter feeders, hermaphroditic, 2 siphones, pharyngeal basket for feeding and gas exchange, u-shaped gut.
What are the key characteristics of the Urochordata class Thaliacea?
Pelagic, gelatinous, sometimes polymorphic, no free-swimming larvae, alternation of generations - salps and doliolids.
What are the key features of the Urochordata class Larvacea?
Pelagic, adults retain notochord, mucus house, paedomorphic.
