Marie Inverts Exam 2

Trochophore larva

A free-swimming larval stage found in some marine invertebrates, characterized by the presence of a band of cilia used for locomotion and feeding.

Planktotrophic

Type of larval development in marine organisms where larvae feed on plankton before metamorphosis. Characteristic of Trochophore larva

Reduced coelom

Type of body cavity found in some invertebrates, where the mesoderm only partially lines the cavity, leaving a small space between the mesoderm and endoderm.

Hypothetical ancestral mollusc (HAM)

An ancestral mollusk that is believed to have existed, based on genetic and morphological evidence. It is thought to have given rise to all modern-day mollusk species, including snails, clams, and octopuses.

List the shared characteristics that many living molluscs appear to have modified versions of.

1. Head-foot - involved with locomotion, feeding and sensory functions
2. visceral mass - digestive, circulatory, and excretory organs
3. mantle - tissue that secretes shell, and forms the protected gill chamber

Visceral mass

A soft, non-segmented body region in mollusks that contains the internal organs, including the digestive, reproductive, and excretory systems. It is located between the head and the foot.

Mantle

The soft tissue layer that covers the body of some invertebrates, such as mollusks and brachiopods, and secretes the shell or protects the body.

Ctenidia

A respiratory organ found in mollusks that helps in gas exchange. It consists of gill filaments and gill lamellae.

Radula

A tongue-like organ found in most mollusks, which is covered with rows of tiny teeth or denticles. It is used to scrape and grind food before it enters the digestive system.

Torsion

the rotation of the visceral mass, mantle, and shell 180˚ with respect to the head and foot of the gastropod

detorsion

reverse torsion

Valves

each articulating part of the shell of a mollusc or another multi-shelled animal such as brachiopods and some crustaceans

Siphons

tube-like structures in which water (or, more rarely, air) flows. The water flow is used for one or more purposes such as locomotion, feeding, respiration, and reproduction

Umbo

slight bulge near the hinge - generally this is where the larval shell begins and elongates away from during growth

Captaula

a snout like proboscis that extends to a tentacle like _____, that is used to capture plankton

Dorso-ventral axis

differentiates the back from the belly

Prehensile tentacles

Tentacles that are capable of grabbing

Chromatophores

allows for modification of appearance (color and texture)

Cuticula

Belonging to class Solenogastres, a chitinous cuticle with calcareous spines that covers the body.

Prosobranchia

Proso = foward; Branchia = gills

visceral mass showing torsion, mantle cavity, gills, genital and excretory and anal openings facing foward.

Opisthobranchia

opistho = rear; branchia = gills

streamlined marine forms showings detorsion, and thus prosterior mantle cavity anf reduced or absent shell and/or gills

Pulmonata

pulmo = lung

usually lacking gills, with a vascularized mantle cavity that serves as a lungbyssal

Byssal threads

threads are strong, silky fibers that are made from proteins that are used by mussels and other bivalves to attach to rocks, pilings or other substrates

Mantle cavity

The space between the mantle and the visceral mass. Respiatory organs typically found here. Develops independently of the coelomic cavity.

Adductor muscle

The main muscular system in clams and other bivalve mollusks. The majority of bivalve species have two adductor muscles located on the anterior and posterior sides of their bodies. Some species of bivalves only have one adductor muscle;

Labial palps

food sorting organs in which a mucus is secreted that entangles suspended food and nutrient particles within the water to produce a ball of food and mucus called a bolus.

hepatopancreas

secretes digestive enzymes

Siphuncle

a strand of tissue passing longitudinally through the shell of a cephalopod mollusk, used primarily in emptying water from new chambers as the shell grows.

collar

section of the mantle on a squid right above the eyes

Metamerism

The phenomenon of having a linear series of body segments fundamentally similar in structure, though not all such structures are entirely alike in any single life form because some of them perform special function

Compound eye

a visual organ found in arthropods such as insects and crustaceans. 

open circulatory system

no blood vessels to carry out the function of blood transportation throughout the body of the organism. There is a mixing of the blood and interstitial fluid. The organs and tissues in the bodies of the organisms are directly fed with blood.

Hemocoel

a body cavity (as in arthropods or some mollusks) that contains blood or hemolymph and functions as part of the circulatory system

Prosoma (cephalothorax)

head (Cephalon) and the thorax fused together

Opisthoma

Following the prosoma tagma, this portion is the abdomen

Chelicerae

a pair of appendages in front of the mouth in arachnids and some other arthropods, usually modified as pincer-like claws

pedipalps

Second pair of appandages

Uniramous appendages

Limbs are not branched

biramous appendages

limbs/legs that have two branches

Uniramous vs. biramous appendages

The key difference between biramous and uniramous arthropods is that biramous arthropods have limbs with two branches, each having a series of segments attached end to end, while uniramous arthropods have limbs with a single series of segments attached end-to-end.

Cephalon

Head segment

Test

barnacle shell, a modified calcareous carapace, which houses the body

Opercular plates

Plates that close off the animal from the environment

barnacle life cycle

Hatch into nauplii then Cyprid, then metamamorphizes into an adult

Cirri

Feather like appandage that are used for feeding 

Exoskeleton

rigid or articulated envelope that supports and protects the soft tissues of certain animals. The term includes the calcareous housings of sessile invertebrates such as clams but is most commonly applied to the chitinous integument of arthropods, such as insects, spiders, and crustaceans.

Ventral nerve cord

a major structure of the invertebrate central nervous system. It is the functional equivalent of the vertebrate spinal cord.

segmental ganglia

are ganglia of the annelid and arthropod central nervous system that lie in the segmented ventral nerve cord.

haemocoel

the primary body cavity of most invertebrates, containing circulatory fluid. 

Malpighian tubule

a type of excretory and osmoregulatory system found in some insects, myriapods, arachnids and tardigrades. The system consists of branching tubules extending from the alimentary canal that absorbs solutes, water, and wastes from the surrounding hemolymph.

Green gland

 If the tubule adjacent to the excretory pore is green

Trachaea

wind pipe in some Arthropds

carapace

dorsal (upper) section of the exoskeleton or shell in a number of animal groups

### telson

the last segment in the abdomen, or a terminal appendage to it, in crustaceans, chelicerates, and embryonic insects.

gnathobases

A lower appendage of many arthropods, used to macerate food items.

Gill Cleaners

usually complemented by dense setae fringing the limb bases and carapace margins, which serve as filter screens for the inhalant water to the gills.

genital operculum

The genital operculum covers and protects the other thoracetronic appendages, as well as bearing the sexual organs 

Book Gill

a gill found in the horseshoe crabs that consists of membranous folds arranged like the leaves of a book 

antennule

a small antenna, especially either of the first pair of antennae in a crustacean.

dorsoventrally depressed

Body is short and wide

lateral spines

spines that poke out the side of the carapace

Anterolateral teeth

smaller spines that emerge from the carapace

Cervival groove

represents the division between the gill/ heart and the stomach internally, or the approximate divsion between the head and thorax

stalked eyes

eyes found on crabs, they sit into the orbits

Orbits

shallow, notched portion of the carapace where the stalked eyes sit

Rostrum

The forward extension of the carapace in front of the eyes.

Perepods

Appendages of thorax segments

Chelipeds (Chelae)

Large claws (first appandages)

Dactyl

top moveable finger of the Chelipeds

Propodus

fixed finger of the Chelipeds

Carpus and merus

segments of the arm

swimming legs

the hind most legs used for swimming

the five segments of the swimmer leg

extending outward from carapace


1. coxa
2. basi-ischium
3. merus
4. carpus
5. propodus and dactyl are flattened

pereon

the thorax or the seven metameres comprising the thorax of some crustaceans (such as a decapod).

maxilliped

(in crustaceans) an appendage modified for feeding, situated in pairs behind the maxillae

apron

the abdomen folded back onto the thorax in decapods

swimmerets

used for transferring sperm

gonopores

in male crabs, secretes sperm

sponge

the area in female crabs where eggs are deposited under the abdomen

ostia

openings in crab hearts in which hemocoel moves in and out

deuterostome

anus forms before mouth

enterocoelous

coelom forms as the digestive system (endoderm) is pinched off, rather than form from within the mesoderm

stomatocoel

The posterior of the three regions of coelomic sacs of the embryonic coelom

pentaradial symmetry

similiar to bilaterally symmetrical, just in rays of 5.

aboral

relating to or denoting the side or end that is furthest from the mouth, especially in animals that lack clear upper and lower sides such as echinoderms

mesodermal skeleton

a spiny skeleton that consists of calcareous ossicles that occasionally project from the epidermis

ossicles

a small piece of calcified material forming part of the skeleton of an invertebrate animal such as an echinoderm

Madreporite

a light colored calcareous opening used to filter water into the water vascular system of echinoderms

Tube feet (podia)

muscular appandages that facilitate movement, adhesion, sensing, and capturing food

ambulacrum

(in an echinoderm) each of the radially arranged bands, together with their underlying structures, through which the double rows of tube feet protrude

Pedicellaria

pincher- like appendages or detect light

haemal

system that may aid in circulation or immune responses

Aristotle’s latern

a jaw-like apparatus used for scraping algae and ither food particles from rocks (seen in urchins).

veliger

Larvae type found in gastropods and bivalves

Ecdysis

Process of shedding the outer layer of skin or exoskeleton in arthropods and reptiles to allow for growth and development.

nauplii

barnacle or copepod larva

Zoea and megalopa

different stages of crab life cycle. Zoea comes before megalopa

water vascular system

a hydraulic system used by echinoderms, such as sea stars and sea urchins. Where it draws water through the madreporite and ends in muscular tube feet (podia) that facilitate movement, adhesion, sensing, and assist in capturing food.

nephridia

functions similarily to kidneys

Protostome

formation of the organism's mouth before its anus during embryonic development