The paralyzing power of the stings and the retractile nature of the tentacles enable the cnidarians to bring to its mouth most small creatures which encounter it. Tentacles covered with cnidocytes (stinging cells) surround the mouth. Their body is a hollow tube open at one end (the mouth). Cnidarians include jellyfish (see zooplankton), and hydroids. In the Gulf of Maine, you will find Northern red anemone ( Urticina felina), red soft coral ( Gersemia rubiformis) and Tubularian or pink-mouthed hydroid ( Ectopleura crocea), to name a few. Sponges can also reproduce by budding off portions of the body.
Larvae then develop within the parent and are released along with the excurrent water. Sperm is released into the water and taken in by other sponges. Most all are hermaphroditic, producing both eggs and sperm. Sponges can reproduce either sexually or asexually. Excess water and wastes pass out through the excurrent pores (oscula).
Sponges are filter feeders, straining out organisms from the water that constantly passes over their pore covered (ostia) bodies. The body of the sponge is supported by a framework of numerous interlocking spicules (crystalline rods) or a tough fabric of protein spongin fibers. Sponges are composed of many individual cells, each carrying out their job of eating, breathing and removing wastes. On Stellwagen, they often encrust shellfish beds or the rare, large boulders left from glaciers. Sponges are relatively primitive animals that live attached to the ocean floor or other hard substrates from the intertidal zone to great depths. Species Descriptions: (by related groups)īoring sponge, Cliona celata, finger sponge, Haliclona oculata and crumb of bread sponge, Halichondria panicea, are a few sponges found on the Bank. Still others are considered completely inedible, yet are used by people in other manners (see the horseshoe crab).Įchinodermata: sea stars, urchins and sand dollars Some of them, like lobster and scallop, have become New England favorites while others, like squid and urchin, are sent to growing markets abroad. As fish stocks in the North Atlantic dwindle, fishing communities are turning to invertebrates as a commercial crop. In the species descriptions below, people may recognize creatures from visits to tidepools or the dinner plate. Currents nourish the younger life stages and distribute these organisms to the far flung reaches of their adult range. Many of the following species are quite familiar as attached creatures in their adult stages, yet most, marine invertebrates spend at least part of their life drifting on currents as zooplankton. This, however, is a somewhat misleading definition. “Other invertebrates” is the term we use to distinguish a whole host of spineless animals that do not drift with the tides like plankton.
Orange-footed sea cucumber and green sea urchins.
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